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(1)

40,099,696 shares of Common Stock, par value $.0001 per share, of Amgen Inc., a Delaware corporation (“Shares”), are being registered hereunder. Such number of Shares represents the aggregate number of Shares issuable (i) pursuant to various equity plans of Immunex Corporation (“Immunex”), which plans are being assumed by Amgen Inc. (the “Company”) in connection with the merger of AMS Acquisition Inc. (“AMS”), a wholly owned subsidiary of the Company, with Immunex (the “Merger”), or (ii) under the Amgen Inc. Profit Sharing 401(k) Plan and Trust (formerly known as the Immunex Corporation Profit Sharing 401(k) Plan and Trust). The number of Shares subject to outstanding awards or rights under the plans as of the closing of the Merger has been calculated pursuant to exchange ratios set forth in the Amended and Restated Agreement and Plan of Merger dated as of December 16, 2001, by and between the Company, AMS, and Immunex, as amended by that certain First Amendment to Amended and Restated Agreement and Plan of Merger dated as of July 15, 2002, and as further amended from time to time (the “Merger Agreement”). The conversion of Shares available under the assumed equity plans but not subject to awards outstanding as of the closing of the Merger has been calculated based on a ratio determined by the Company in accordance with the terms of the plans. The Shares consist of: (A) 18,529,954 Shares issuable under the Amgen Inc. Amended and Restated 1993 Equity Incentive Plan (formerly known as the Immunex Corporation 1993 Stock Option Plan); (B) 19,274,402 Shares issuable under the Amgen Inc. Amended and Restated 1999 Equity Incentive Plan (formerly known as the Immunex Corporation 1999 Stock Option Plan); (C) 1,298,005 Shares issuable under the Amgen Inc. Amended and Restated 1999 Employee Stock Purchase Plan (formerly known as the Immunex Corporation 1999 Employee Stock Purchase Plan); (D) 347,880 Shares issuable under the Immunex Corporation Stock Option Plan for Nonemployee Directors, as amended; and (E) 649,455 Shares issuable under the Amgen Inc. Profit Sharing 401(k) Plan and Trust (formerly known as the Immunex Corporation Profit Sharing 401(k) Plan and Trust). Pursuant to Rule 416 under the Securities Act of 1933, as amended (the “Securities Act”), the amount registered hereunder includes an indeterminate number of Shares that may be issued in accordance with the provisions of such plans in connection with any anti-dilution provisions or in the event of any change in the outstanding Shares, including a stock dividend or stock split. In addition, pursuant to Rule 416(c) under the Securities Act, this Registration Statement also covers an indeterminate amount of interests to be offered or sold pursuant to the Amgen Inc. Profit Sharing 401(k) Plan and Trust (formerly known as the Immunex Corporation Profit Sharing 401(k) Plan and Trust) described herein.

(2)

Estimated solely for the purpose of calculating the registration fee pursuant to Rule 457(h) and (c) of the Securities Act, based upon: (A) the average of the high and low prices of the Company’s Shares as reported on the Nasdaq National Market on July 15, 2002 ($32.17) for 17,670,297 Shares, consisting of (i) 1,358,285 Shares available for issuance pursuant to future awards under the Amgen Inc. Amended and Restated 1993 Equity Incentive Plan (formerly known as the Immunex Corporation 1993 Stock Option Plan); (ii) 14,364,552 Shares available for issuance pursuant to future awards under the Amgen Inc. Amended and Restated 1999 Equity Incentive Plan (formerly known as the Immunex Corporation 1999 Stock Option Plan); (iii) 1,298,005 Shares issuable under the Amgen Inc. Amended and Restated 1999 Employee Stock Purchase Plan (formerly known as the Immunex Corporation 1999 Employee Stock Purchase Plan); and (iv) 649,455 Shares issuable under the Amgen Inc. Profit Sharing 401(k) Plan and Trust (formerly known as the Immunex Corporation Profit Sharing 401(k) Plan and Trust); and (B) the weighted average exercise price per share ($ 23.58) with respect to outstanding awards for 22,429,399 Shares, consisting of (i) 347,880 Shares under the Immunex Corporation Stock Option Plan for Nonemployee Directors, as amended; (ii) 17,171,669 Shares under the Amgen Inc. Amended and Restated 1993 Equity Incentive Plan (formerly known as the Immunex Corporation 1993 Stock Option Plan); and (iii) 4,909,850 Shares under the Amgen Inc. Amended and Restated 1999 Equity Incentive Plan (formerly known as the Immunex Corporation 1999 Stock Option Plan).

(3)

Computed in accordance with Section 6(b) of the Securities Act, by multiplying 0.000092 by the proposed maximum aggregate offering price.

(4)

The preferred share purchase rights, which are attached to the Shares being registered hereunder, will be issued for no additional consideration. Accordingly, no additional registration fee is payable.

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A.

The Company’s Annual Report on Form 10-K for the year ended December 31, 2001;

B.

The Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2002;

C.

The Company’s Current Reports on Form 8-K filed on March 1, 2002, May 10, 2002, and May 22, 2002; and

D.

Description of the Company’s Common Stock, contractual contingent payment rights and preferred share purchase rights contained in the Registration Statements on Form 8-A filed with the Commission on September 7, 1983 and April 1, 1993, and the Forms 8-K filed with the Commission on February 28, 1997 and December 18, 2000, respectively, including any amendment or report filed for the purpose of updating that description.

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*

Filed herewith.

(1)

To file, during any period in which offers or sales are being made, a post-effective amendment to this Registration Statement:

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(ii)

To reflect in the prospectus any facts or events arising after the effective date of this Registration Statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the Registration Statement;

(iii)

To include any material information with respect to the plan of distribution not previously disclosed in the Registration Statement or any material change to such information in the Registration Statement;

(2)

That, for the purpose of determining any liability under the Securities Act, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(3)

To remove from registration by means of a post-effective amendment any of the securities being registered that remain unsold at the termination of the offering.

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Filed herewith.

                                                                     EXHIBIT 5.1

                        [LETTERHEAD OF LATHAM & WATKINS]

                                  July 15, 2002

Amgen Inc.
One Amgen Center Drive
Thousand Oaks, California 91320-1799


     Re:  Registration Statement on Form S-8 of Common Stock, $0.0001 par value
          ---------------------------------------------------------------------
          per share
          ---------

Ladies and Gentlemen:

     In connection with the registration by Amgen Inc., a Delaware corporation
(the "Company"), of 40,099,696 shares of its common stock, par value $0.0001 per
share (the "Shares"), under the Securities Act of 1933, as amended, on the
Registration Statement on Form S-8 filed with the Securities and Exchange
Commission on July 16, 2002 (the "Registration Statement"), issuable pursuant to
the Plans (as defined below), you have requested our opinion with respect to the
matters set forth below. For purposes of this opinion, "Plans" shall mean the
Amgen Inc. Amended and Restated 1993 Equity Incentive Plan (formerly known as
the Immunex Corporation 1993 Stock Option Plan), the Amgen Inc. Amended and
Restated 1999 Equity Incentive Plan (formerly known as the Immunex Corporation
1999 Stock Option Plan), the Amgen Inc. Amended and Restated 1999 Employee Stock
Purchase Plan (formerly known as the Immunex Corporation 1999 Employee Stock
Purchase Plan), the Immunex Corporation Stock Option Plan for Nonemployee
Directors, as amended, and the Amgen Inc. Profit Sharing 401(k) Plan and Trust
(formerly known as the Immunex Corporation Profit Sharing 401(k) Plan and
Trust).

     In our capacity as your counsel in connection with such registration, we
are familiar with the proceedings taken and proposed to be taken by the Company
in connection with the authorization and issuance of the Shares, and for the
purposes of this opinion, have assumed such proceedings will be timely completed
in the manner presently proposed. In addition, we have made such legal and
factual examinations and inquiries, including an examination of originals or
copies certified or otherwise identified to our satisfaction of such documents,
corporate records and instruments, as we have deemed necessary or appropriate
for purposes of this opinion.



Latham & Watkins
July 15, 2002
Page 2

     In our examination, we have assumed the genuineness of all signatures, the
authenticity of all documents submitted to us as originals, and the conformity
to authentic original documents of all documents submitted to us as copies.

     As to facts material to the opinions, statements and assumptions expressed
herein, we have, with your consent, relied upon oral or written statements and
representations of officers and other representatives of the Company and others.
In addition, we have obtained and relied upon such certificates and assurances
from public officials as we have deemed necessary.

     We are opining herein as to the effect on the subject transaction only of
the General Corporation Law of the State of Delaware, and we express no opinion
with respect to the applicability thereto, or the effect thereon, of the laws of
any other jurisdiction or, in the case of Delaware, any other laws, or as to any
matters of municipal law or the laws of any local agencies within any state.

     Subject to the foregoing, it is our opinion that the Shares have been duly
authorized, and, upon the issuance of the Shares in accordance with the terms of
the Plans, and delivery and payment therefor of legal consideration in excess of
the aggregate par value of the Shares issued, such Shares will be validly
issued, fully paid and nonassessable.

     We consent to your filing this opinion as an exhibit to the Registration
Statement.

                                        Very truly yours,

                                        /s/ Latham & Watkins

                                                                    EXHIBIT 10.1

                                   AMGEN INC.

                 AMENDED AND RESTATED 1993 EQUITY INCENTIVE PLAN

     Amgen Inc. has adopted this Amended and Restated 1993 Equity Incentive Plan
(the "Plan"), effective as of July 15, 2002 (the "Restatement Date"). This Plan
amends and restates in its entirety the Immunex Corporation 1993 Stock Option
Plan, as amended (the "Original Plan").

                                   ARTICLE I.

                    PROVISIONS APPLICABLE TO OPTIONS GRANTED
                            PRIOR TO RESTATEMENT DATE

     The following provisions of this Article I shall govern awards granted
under the Plan prior to the Restatement Date:

SECTION 1. PURPOSE.

     The purpose of Article I of the Plan is to provide a means whereby selected
employees, directors and officers of Amgen Inc., a Delaware corporation (the
"Company"), or of any parent or subsidiary (as defined in Article I, subsection
5.8 and referred to hereinafter as "related corporations") thereof, may be
granted incentive stock options and/or nonqualified stock options to purchase
the Common Stock (as defined in Article I, Section 3) of the Company, in order
to attract and retain the services or advice of such employees, directors and
officers and to provide added incentive to such persons by encouraging stock
ownership in the Company.

SECTION 2. ADMINISTRATION.

     This Plan shall be administered by a committee (the "Committee" or "Plan
Administrator") appointed by the Board of Directors of the Company (the "Board")
consisting of two or more members of the Board. If and so long as the Common
Stock is registered under Section 12(b) or 12(g) of the Securities Exchange Act
of 1934, as amended from time to time (the "Exchange Act"), the Board shall
consider in selecting the Plan Administrator and the membership of any committee
acting as Plan Administrator of the Plan with respect to any



persons subject or likely to become subject to Section 16 under the Exchange Act
the provisions regarding (a) "outside directors" as contemplated by Section
162(m) of the Internal Revenue Code of 1986, as amended (the "Code"), and (b)
"nonemployee directors" as contemplated by Rule 16b-3 under the Exchange Act.
The Board may delegate the responsibility for administering the Plan with
respect to designated classes of eligible Participants to different committees,
subject to such limitations as the Board deems appropriate. Committee members
shall serve for such term as the Board may determine, subject to removal by the
Board at any time. To the extent consistent with applicable law, the Board may
authorize one or more senior executive officers of the Company to grant options
to specified eligible persons, within the limits specifically prescribed by the
Board.

     2.1   Procedures.

     The Board shall designate one of the members of the Plan Administrator as
chairman. The Plan Administrator may hold meetings at such times and places as
it shall determine. The acts of a majority of the members of the Plan
Administrator present at meetings at which a quorum exists, or acts reduced to
or approved in writing by all Plan Administrator members, shall be valid acts of
the Plan Administrator.

     2.2   Responsibilities.

     Except for the terms and conditions explicitly set forth in this Plan, the
Plan Administrator shall have the authority, in its discretion, to determine all
matters relating to the options to be granted under this Plan, including
selection of the individuals to be granted options, the number of shares to be
subject to each option, the exercise price, and all other terms and conditions
of the options. Grants under this Plan need not be identical in any respect,
even when made simultaneously. The interpretation and construction by the Plan
Administrator of any terms or provisions of this Plan or any option issued
hereunder, or of any rule or regulation promulgated in connection herewith,
shall be conclusive and binding on all interested parties, so long as such
interpretation and construction with respect to incentive stock options
correspond to the requirements of Section 422 of the Code, the regulations
thereunder and any amendments thereto.

                                       2



     2.3   Section 16(b) Compliance and Bifurcation of Plan.

     Notwithstanding anything in this Plan to the contrary, the Board, in its
absolute discretion, may bifurcate this Plan so as to restrict, limit or
condition the use of any provision of this Plan to participants who are officers
and directors subject to Section 16 of the Exchange Act without so restricting,
limiting or conditioning this Plan with respect to other participants.

SECTION 3. STOCK SUBJECT TO THIS PLAN.

     The stock subject to this Plan shall be the Company's Common Stock, par
value $.0001 per share (the "Common Stock"), presently authorized but unissued.

SECTION 4. ELIGIBILITY.

     An incentive stock option may be granted only to an individual who, at the
time the option is granted, is an employee of the Company or any related
corporation. A nonqualified stock option may be granted to any employee,
director or officer of the Company or any related corporation, whether an
individual or an entity. Any party to whom an option is granted under Article I
of this Plan shall be referred to hereinafter as an "Optionee."

SECTION 5. TERMS AND CONDITIONS OF OPTIONS.

     Options granted under this Plan shall be evidenced by written agreements
which shall contain such terms, conditions, limitations and restrictions as the
Plan Administrator shall deem advisable and which are not inconsistent with this
Plan. Notwithstanding the foregoing, options shall include or incorporate by
reference the following terms and conditions:

     5.1   Number of Shares and Price.

     The maximum number of shares that may be purchased pursuant to the exercise
of each option and the price per share at which such option is exercisable (the
"exercise price") shall be as established by the Plan Administrator; provided,
however, that the Plan Administrator shall act in good faith to establish the
exercise price which shall be not less than the fair market value per share of
the Common Stock at the time the option is granted with respect to incentive
stock options and not less than the par value per share of the Common Stock at
the time the option is

                                       3



granted with respect to nonqualified stock options and also provided that, with
respect to incentive stock options granted to greater than 10% stockholders, the
exercise price shall be as required by Article I, subsection 6.1.

     5.2   Term and Maturity.

     Subject to the restrictions contained in Article I, Section 6 with respect
to granting incentive stock options to greater than 10% stockholders, the term
of each incentive stock option shall be as established by the Plan Administrator
and, if not so established, shall be 10 years from the date it is granted but in
no event shall it exceed 10 years. The term of each nonqualified stock option
shall be as established by the Plan Administrator and, if not so established,
shall be 10 years. To ensure that the Company or related corporation will
achieve the purpose and receive the benefits contemplated in this Plan, any
option granted to any Optionee hereunder shall, unless the condition of this
sentence is waived or modified in the agreement evidencing the option or by
resolution adopted at any time by the Plan Administrator, be exercisable
according to the following schedule:

Period of Optionee's Continuous Relationship
   With the Company or Related Corporation           Portion of Total Option
     From the Date the Option Is Granted               Which Is Exercisable
     -----------------------------------               --------------------

               after one year                                   20%
              after two years                                   40%
             after three years                                  60%
              after four years                                  80%
              after five years                                 100%

     Notwithstanding the foregoing, for any option granted under Article I of
the Plan, the option shall become 100% vested and exercisable on the date of
termination of an Optionee's employment or service relationship with the Company
or a related corporation on account of the Optionee's death, provided that the
Optionee has been in the continuous employment of or service to the Company or a
related corporation for at least two years at the date of such Optionee's death.

                                       4



     5.3   Exercise.

     Subject to the vesting schedule described in Article I, subsection 5.2,
each option may be exercised in whole or in part at any time and from time to
time; provided, however, that no fewer than 20% of the shares purchasable under
the option (or the remaining shares then purchasable under the option, if less
than 20%) may be purchased upon any exercise of option rights hereunder and that
only whole shares will be issued pursuant to the exercise of any option and that
the exercise price shall not be less than the par value per share of the Common
Stock at the time the option is exercised. During an Optionee's lifetime, any
options granted under Article I of this Plan are personal to him or her and are
exercisable solely by such Optionee. Options shall be exercised by delivery to
the Company of notice of the number of shares with respect to which the option
is exercised, together with payment of the exercise price.

     5.4   Payment of Exercise Price.

     Payment of the option exercise price shall be made in full at the time the
notice of exercise of the option is delivered to the Company and shall be in
cash, bank certified or cashier's check or personal check (unless at the time of
exercise the Plan Administrator in a particular case determines not to accept a
personal check) for the Common Stock being purchased.

     The Plan Administrator can determine at any time before exercise that
additional forms of payment will be permitted. To the extent permitted by
applicable laws and regulations (including, but not limited to, federal tax and
securities laws and regulations and state corporate law), and unless the Plan
Administrator determines otherwise, an option also may be exercised, either
singly or in combination with one or more of the alternative forms of payment
authorized by this Article I, Section 5.4 by:

     (a)   tendering (either actually or by attestation) shares of stock of the
Company held by an Optionee having a fair market value equal to the exercise
price, such fair market value to be determined in good faith by the Plan
Administrator; provided, however, that payment in stock held by an Optionee
shall not be made unless the stock shall have been owned by the Optionee for a
period of at least six months (or any shorter period necessary to avoid a charge
to the Company's earnings for financial accounting purposes); or

                                       5



     (b)   delivery of a properly executed exercise notice, together with
irrevocable instructions to a broker, all in accordance with the regulations of
the Federal Reserve Board, to promptly deliver to the Company the amount of sale
or loan proceeds to pay the exercise price and any federal, state or local
withholding tax obligations that may arise in connection with the exercise.

     In addition, the exercise price for shares purchased under an option may be
paid, either singly or in combination with one or more of the alternative forms
of payment authorized by this Article I, Section 5.4, by (y) delivery of a
full-recourse promissory note executed by the Optionee; provided that (i) such
note delivered in connection with an incentive stock option shall, and such note
delivered in connection with a nonqualified stock option may, in the sole
discretion of the Plan Administrator, bear interest at a rate specified by the
Plan Administrator but in no case less than the rate required to avoid
imputation of interest (taking into account any exceptions to the imputed
interest rules) for federal income tax purposes, (ii) the Plan Administrator in
its sole discretion shall specify the term and other provisions of such note at
the time an incentive stock option is granted or at any time prior to exercise
of a nonqualified stock option, (iii) the Plan Administrator may require that
the Optionee pledge to the Company for the purpose of securing the payment of
such note the shares of Common Stock to be issued to the Optionee upon exercise
of the option and may require that the certificate representing such shares be
held in escrow in order to perfect the Company's security interest, and (iv) the
Plan Administrator in its sole discretion may at any time restrict or rescind
this right upon notification to the Optionee; or (z) such other consideration as
the Plan Administrator may permit.

     5.5   Withholding Tax Requirement.

     The Company or any related corporation shall have the right to retain and
withhold from any payment of cash or Common Stock under this Plan the amount of
taxes required by any government to be withheld or otherwise deducted and paid
with respect to such payment. At its discretion, the Company may require an
Optionee receiving shares of Common Stock to reimburse the Company for any such
taxes required to be withheld by the Company and withhold any distribution in
whole or in part until the Company is so reimbursed. In lieu thereof, the
Company shall have the right to withhold from any other cash amounts due or to
become due from the Company to the Optionee an amount equal to such taxes. The
Company may also retain and withhold or the Optionee may elect, subject to
approval by the Company at

                                       6



its sole discretion, to have the Company retain and withhold a number of shares
having a market value not less than the amount of such taxes required to be
withheld by the Company to reimburse the Company for any such taxes and cancel
(in whole or in part) any such shares so withheld.

     5.6   Holding Periods.

           5.6.1  Securities Exchange Act Section 16.

     If an individual subject to Section 16 of the Exchange Act sells shares of
Common Stock obtained upon the exercise of a stock option within six months
after the date the option was granted, such sale may result in short-swing
profit recovery under Section 16(b) of the Exchange Act.

           5.6.2  Taxation of Stock Options.

     The Plan Administrator may require an Optionee to give the Company prompt
notice of any disposition of shares of Common Stock acquired by the exercise of
an incentive stock option prior to the expiration of two years after the date of
grant of the option and one year from the date of exercise.

     5.7   Nontransferability of Options.

     Options granted under Article I of this Plan and the rights and privileges
conferred hereby may not be transferred, assigned, pledged or hypothecated in
any manner (whether by operation of law or otherwise), other than by will or by
the applicable laws of descent and distribution and shall not be subject to
execution, attachment or similar process. Any attempt to transfer, assign,
pledge, hypothecate or otherwise dispose of any option under Article I of this
Plan or of any right or privilege conferred hereby, contrary to the Code or to
the provisions of this Plan, or the sale or levy or any attachment or similar
process upon the rights and privileges conferred hereby shall be null and void.
Notwithstanding the foregoing, if the Company permits, an Optionee may, during
the Optionee's lifetime, designate a person who may exercise the option after
the Optionee's death by giving written notice of such designation to the Plan
Administrator. Such designation may be changed from time to time by the Optionee
by giving

                                       7



written notice to the Plan Administrator revoking any earlier designation and
making a new designation.

     5.8   Termination of Relationship.

     If the Optionee's relationship with the Company or any related corporation
ceases for any reason other than termination for cause, death or total
disability, and unless by its terms the option sooner terminates or expires,
then the portion of the option which is not exercisable at the time of such
cessation shall terminate immediately upon such cessation, unless the Plan
Administrator determines otherwise, and the Optionee may exercise, for a
three-month period, that portion of the option which is exercisable at the time
of such cessation, and shall terminate at the end of such period following such
cessation as to all shares for which it has not theretofore been exercised,
unless the Plan Administrator determines otherwise. The Plan Administrator shall
have sole discretion in a particular circumstance to extend the exercise period
following such cessation to any date up to the termination or expiration of the
option. If, however, in the case of an incentive stock option, the Optionee does
not exercise the Optionee's option within three months after cessation of
employment, the option will no longer qualify as an incentive stock option under
the Code.

     If an Optionee is terminated for cause, any option granted hereunder shall
automatically terminate as of the first discovery by the Company of any reason
for termination for cause, and such Optionee shall thereupon have no right to
purchase any shares pursuant to such option. "Termination for cause" shall mean
dismissal for dishonesty, conviction or confession of a crime punishable by law
(except minor violations), fraud, misconduct or disclosure of confidential
information.

     If an Optionee's relationship with the Company or any related corporation
is suspended pending an investigation of whether or not the Optionee shall be
terminated for cause, all the Optionee's rights under any option granted
hereunder likewise shall be suspended during the period of investigation.

     If an Optionee's relationship with the Company or any related corporation
ceases because of a total disability, the portion of the Optionee's option that
is exercisable at the time of such cessation shall not terminate or, in the case
of an incentive stock option, cease to be treated as an incentive stock option
until the end of the 12-month period following such

                                       8



cessation (unless by its terms it sooner terminates and expires). As used in
this Plan, the term "total disability" refers to a mental or physical impairment
of the Optionee which is expected to result in death or which has lasted or is
expected to last for a continuous period of 12 months or more and which causes
the Optionee to be unable, in the opinion of the Company and two independent
physicians, to perform his or her duties for the Company and to be engaged in
any substantial gainful activity. Total disability shall be deemed to have
occurred on the first day after the Company and the two independent physicians
have furnished their opinion of total disability to the Plan Administrator.

     Options granted under Article I of this Plan shall not be affected by any
change of relationship with the Company so long as the Optionee continues to be
an employee, director, officer, agent, consultant, advisor or independent
contractor of the Company or of a related corporation. The Plan Administrator,
in its absolute discretion, may determine all questions of whether particular
leaves of absence constitute a termination of services; provided, however, that
with respect to incentive stock options, such determination shall be subject to
any requirements contained in the Code. The foregoing notwithstanding, with
respect to incentive stock options, employment shall not be deemed to continue
beyond the first 90 days of such leave, unless the Optionee's reemployment
rights are guaranteed by statute or by contract.

     As used herein, the term "related corporation," when referring to a
subsidiary corporation, shall mean any corporation (other than the Company) in,
at the time of the granting of the option, an unbroken chain of corporations
ending with the Company, if stock possessing 50% or more of the total combined
voting power of all classes of stock of each of the corporations other than the
Company is owned by one of the other corporations in such chain. When referring
to a parent corporation, the term "related corporation" shall mean any
corporation in an unbroken chain of corporations ending with the Company if, at
the time of the granting of the option, each of the corporations other than the
Company owns stock possessing 50% or more of the total combined voting power of
all classes of stock in one of the other corporations in such chain.

     5.9   Death of Optionee.

     If an Optionee dies while he or she has a relationship with the Company or
any related corporation or within the three-month period (or 12-month period in
the case of totally disabled Optionees) following cessation of such
relationship, any option held by such Optionee to the

                                       9



extent that the Optionee would have been entitled to exercise such option, may
be exercised within one year after his or her death by the personal
representative of his or her estate or by the person or persons to whom the
Optionee's rights under the option shall pass by will or by the applicable laws
of descent and distribution.

     5.10  No Status As Stockholder.

     Neither the Optionee nor any party to which the Optionee's rights and
privileges under the option may pass shall be, or have any of the rights or
privileges of, a stockholder of the Company with respect to any of the shares
issuable upon the exercise of any option granted under this Plan unless and
until such option has been exercised.

     5.11  Continuation of Relationship.

     Nothing in this Plan or in any option granted pursuant to this Plan shall
confer upon any Optionee any right to continue in the employ or other
relationship of the Company or of a related corporation, or to interfere in any
way with the right of the Company or of any such related corporation to
terminate his or her employment or other relationship with the Company at any
time.

     5.12  Modification and Amendment of Option.

     Subject to the requirements of Section 422 of the Code with respect to
incentive stock options and to the terms and conditions and within the
limitations of this Plan, the Plan Administrator may modify or amend outstanding
options granted under Article I of this Plan. The modification or amendment of
an outstanding option shall not, without the consent of the Optionee, impair or
diminish any of his or her rights or any of the obligations of the Company under
such option. Except as otherwise provided in this Plan, no outstanding option
shall be terminated without the consent of the Optionee. Unless the Optionee
agrees otherwise, any changes or adjustments made to outstanding incentive stock
options granted under this Plan shall be made in such a manner so as not to
constitute a "modification" as defined in Section 424(h) of the Code and so as
not to cause any incentive stock option issued hereunder to fail to continue to
qualify as an incentive stock option as defined in Section 422(b) of the Code.

                                       10



     5.13   Limitation on Value for Incentive Stock Options.

     As to all incentive stock options granted under the terms of this Plan, to
the extent that the aggregate fair market value of the stock (determined at the
time the incentive stock option is granted) with respect to which incentive
stock options are exercisable for the first time by the Optionee during any
calendar year (under this Plan and all other incentive stock option plans of the
Company, a related corporation or a predecessor corporation) exceeds $100,000,
such options shall be treated as nonqualified stock options. The previous
sentence shall not apply if the Internal Revenue Service issues a statutory
change, public rule, issues a private ruling to the Company, any Optionee or any
legatee, personal representative or distributee of an Optionee or issues
regulations changing or eliminating such annual limit.

SECTION 6. GREATER THAN 10% STOCKHOLDERS.

     6.1    Exercise Price and Term of Incentive Stock Options.

     If incentive stock options are granted under this Plan to employees who own
more than 10% of the total combined voting power of all classes of stock of the
Company or any related corporation, the term of such incentive stock options
shall not exceed five years and the exercise price shall be not less than 110%
of the fair market value of the Common Stock at the time the incentive stock
option is granted. This provision shall control notwithstanding any contrary
terms contained in an option agreement or any other document.

     6.2    Attribution Rule.

     For purposes of Article I, subsection 6.1, in determining stock ownership,
an employee shall be deemed to own the stock owned, directly or indirectly, by
or for his or her brothers, sisters, spouse, ancestors and lineal descendants.
Stock owned, directly or indirectly, by or for a corporation, partnership,
estate or trust shall be deemed to be owned proportionately by or for its
stockholders, partners or beneficiaries. If an employee or a person related to
the employee owns an unexercised option or warrant to purchase stock of the
Company, the stock subject to that portion of the option or warrant which is
unexercised shall not be counted in determining stock ownership. For purposes of
this Article I, Section 6, stock owned by an employee shall include all stock
actually issued and outstanding immediately before the grant of the incentive
stock option to the employee.

                                       11



SECTION 7. ADJUSTMENTS UPON CHANGES IN CAPITALIZATION.

     The aggregate number and class of shares for which options may be granted
under this Plan, the number and class of shares covered by each outstanding
option and the exercise price per share thereof (but not the total price), shall
all be proportionately adjusted for any increase or decrease in the number of
issued shares of Common Stock resulting from a split-up or consolidation of
shares or any like capital adjustment, or the payment of any stock dividend.

     7.1   Effect of Liquidation or Reorganization.

           7.1.1  Cash, Stock or Other Property for Stock.

     Except as provided in Article I, subsection 7.1.2, upon a merger (other
than a merger of the Company in which the holders of Common Stock immediately
prior to the merger have the same proportionate ownership of Common Stock in the
surviving corporation immediately after the merger), consolidation, acquisition
of property or stock, separation, reorganization (other than a mere
reincorporation or the creation of a holding company) or liquidation of the
Company, as a result of which the stockholders of the Company receive cash,
stock or other property in exchange for or in connection with their shares of
Common Stock, any option granted hereunder shall terminate, but the Optionee
shall have the right immediately prior to any such merger, consolidation,
acquisition of property or stock, liquidation or reorganization to exercise such
Optionee's option in whole or in part whether or not the vesting requirements
set forth in the option agreement have been satisfied.

           7.1.2  Conversion of Options on Stock for Stock Exchange.

     If the stockholders of the Company receive capital stock of another
corporation ("Exchange Stock") in exchange for their shares of Common Stock in
any transaction involving a merger (other than a merger of the Company in which
the holders of Common Stock immediately prior to the merger have the same
proportionate ownership of Common Stock in the surviving corporation immediately
after the merger), consolidation, acquisition of property or stock, liquidation
or reorganization (other than a mere reincorporation or the creation of a
holding company), the Company and the corporation issuing the Exchange Stock, in
their sole discretion, may determine that all options granted hereunder shall be
converted into options to

                                       12



purchase shares of Exchange Stock instead of terminating in accordance with the
provisions of Article I, subsection 7.1.1. The amount and price of converted
options shall be determined by adjusting the amount and price of the options
granted hereunder in the same proportion as used for determining the number of
shares of Exchange Stock the holders of the Common Stock receive in such merger,
consolidation, acquisition of property or stock, liquidation or reorganization.
Unless accelerated by the Board, the vesting schedule set forth in the option
agreement shall continue to apply to the options granted for the Exchange Stock.
The aggregate number and kind of shares for which options may be granted under
this Plan shall be proportionately adjusted in the event of such merger,
consolidation, acquisition of property or stock, liquidation or reorganization.

     7.2   Fractional Shares.

     In the event of any adjustment in the number of shares covered by any
option, any fractional shares resulting from such adjustment shall be
disregarded and each such option shall cover only the number of full shares
resulting from such adjustment.

     7.3   Determination of Board to Be Final.

     All Article I, Section 7 adjustments shall be made by the Plan
Administrator, and its determination as to what adjustments shall be made, and
the extent thereof, shall be final, binding and conclusive. Unless an Optionee
agrees otherwise, any change or adjustment to an incentive stock option shall be
made in such a manner so as not to constitute a "modification" as defined in
Section 424(h) of the Code and so as not to cause his or her incentive stock
option issued hereunder to fail to continue to qualify as an incentive stock
option as defined in Section 422(b) of the Code.

SECTION 8. SECURITIES REGULATION.

     Shares shall not be issued with respect to an option granted under this
Plan unless the exercise of such option and the issuance and delivery of such
shares pursuant thereto shall comply with all relevant provisions of law,
including, without limitation, any applicable state securities laws, the
Securities Act of 1933, as amended, the Exchange Act, the rules and regulations
promulgated thereunder, and the requirements of any stock exchange upon which
the shares may then be listed, and shall be further subject to the approval of
counsel for the

                                       13



Company with respect to such compliance, including the availability, if
applicable of an exemption from registration for the issuance and sale of any
shares hereunder.

SECTION 9. AMENDMENT AND TERMINATION.

      9.1   Board Action.

      The Board may at any time suspend, amend or terminate this Plan, provided
that except as set forth in Article I, Section 7, and to the extent required for
compliance with Section 422 of the Code or Section 162(m) of the Code or by any
applicable law or requirement, the Company's stockholders must approve within 12
months of the adoption by the Board any amendment which will:

      (a)   increase the total number of shares that may be issued under this
            Plan;

      (b)   modify the class of participants eligible for participation in this
            Plan; or

      (c)   otherwise require stockholder approval under any applicable law or
            regulation.

      Any amendment made to this Plan since its original adoption which would
constitute a "modification" to incentive stock options outstanding on the date
of such amendment, shall not be applicable to such outstanding incentive stock
options, but shall have prospective effect only, unless the Optionee agrees
otherwise.

      9.2   Automatic Termination.

     Unless sooner terminated by the Board, this Plan shall terminate ten years
from the earlier of (a) the date on which this Plan was adopted by the Board of
Directors of Immunex Corporation ("Immunex") or (b) the date on which this Plan
was approved by the stockholders of Immunex. No option may be granted after such
termination or during any suspension of this Plan. The amendment or termination
of this Plan shall not, without the consent of the Optionee, impair or diminish
any rights or obligations under any option theretofore granted under this Plan.

                                       14



SECTION 10. EFFECTIVENESS OF THIS PLAN.

     The Original Plan became effective upon adoption by the Board of Directors
of Immunex, and was approved by a majority of stock represented by stockholders
voting either in person or by proxy at a duly held stockholders' meeting within
12 months before or after the adoption of the Original Plan.

Section 11.  ADDENDUM TO ARTICLE I OF THE PLAN.

     Notwithstanding anything in Article I of the Plan to the contrary,
effective as of the Effective Time (as defined in the Amended and Restated
Agreement and Plan of Merger by and between the Company, AMS Acquisition Inc.
and Immunex dated as of December 16, 2001 as amended by that certain First
Amendment to Amended and Restated Agreement and Plan of Merger dated as of July
15, 2002 (as amended, the "Merger Agreement")), the following provisions shall
constitute an addendum (the "Addendum") to Article I of the Plan:

     11.1.  At the Effective Time, each option granted pursuant Article I of the
Plan shall be treated in accordance with the applicable terms of the Merger
Agreement.

     11.2.  In the event that an optionee's employment with Immunex or the
Company is terminated by the optionee for Good Reason or by Immunex or the
Company without Cause during the fifteen (15) months following the Effective
Time, each option held by such optionee for Common Stock that was granted
pursuant to the Merger Agreement with respect to (a) a Cancelled Company Option
(as defined in the Merger Agreement) or (b) an option for common stock of
Immunex that was granted after December 16, 2001, shall immediately vest in full
and shall remain exercisable until the earlier of (x) the first anniversary of
the optionee's termination of employment or (y) the end of the term of such
option.

     11.3.  For purposes of this Addendum only, "Good Reason" shall mean the
occurrence on or after the Effective Time and without the optionee's consent of,
(a) a reduction in the optionee's annual base salary or wages, other than as
part of a general reduction applicable to substantially all employees of Immunex
or the Company employed in the United States or (ii) the relocation of the
optionee's principal place of employment to a location more than fifty (50)
miles from the optionee's principal place of employment prior to the Effective
Time.

                                       15



      11.4. For purposes of this Addendum only, "Cause" shall mean (a) the
willful and continued failure by the optionee to substantially perform the
optionee's duties with Immunex or the Company (other than such failure resulting
form the optionee's incapacity due to physical or mental illness) or (b) the
willful engaging by the optionee in conduct which is demonstrably and materially
injurious to Immunex or the Company, monetarily or otherwise. For purposes of
this definition, no act, or failure to act, on the optionee's part shall be
deemed willful unless done, or omitted to be done, by the optionee not in good
faith or without reasonable belief that the optionee's act, or failure to act,
was in the best interest of Immunex or the Company.

                                   ARTICLE II.

                    PROVISIONS APPLICABLE TO OPTIONS GRANTED
                          ON OR AFTER RESTATEMENT DATE

     The following provisions of this Article II shall govern awards granted
under the Plan on or after the Restatement Date:

SECTION 1.  PURPOSE.

      (a)   The purpose of Article II of the Plan is to provide a means by which
employees or directors of and consultants to Amgen Inc., a Delaware corporation
(the "Company"), and its Affiliates, as defined in Article II, paragraph 1(b),
directly, or indirectly through Trusts, may be given an opportunity to benefit
from increases in value of the stock of the Company through the granting of (i)
incentive stock options, (ii) nonqualified stock options, (iii) stock bonuses,
and (iv) rights to purchase restricted stock, all as defined below.

      (b)   The word "Affiliate" as used in Article II of the Plan means any
parent corporation or subsidiary corporation of the Company, as those terms are
defined in Sections 424(e) and (f), respectively, of the Internal Revenue Code
of 1986, as amended (the "Code").

      (c)   The Company, by means of Article II of the Plan, seeks to retain the
services of persons now employed by or serving as directors or consultants to
the Company, to secure and retain the services of persons capable of filling
such positions, and to provide incentives for such persons to exert maximum
efforts for the success of the Company.

                                       16



      (d)   The Company intends that the rights issued under Article II of the
Plan ("Stock Awards") shall, in the discretion of the Board of Directors of the
Company (the "Board") or any committee to which responsibility for
administration of the Plan has been delegated pursuant to Article II, paragraph
2(c), be either (i) stock options granted pursuant to Article II, Sections 5 or
6 hereof, including incentive stock options as that term is used in Section 422
of the Code ("Incentive Stock Options"), or options which do not qualify as
Incentive Stock Options ("Nonqualified Stock Options") (together hereinafter
referred to as "Options"), or (ii) stock bonuses or rights to purchase
restricted stock granted pursuant to Article II, Section 7 hereof.

      (e)   The word "Trust" as used in Article II of the Plan shall mean a
trust created for the benefit of the employee, director or consultant, his or
her spouse, or members of their immediate family. The word optionee shall mean
the person to whom the option is granted or the employee, director or consultant
for whose benefit the option is granted to a Trust, as the context shall
require.

SECTION 2.  ADMINISTRATION.

      (a)   The Plan shall be administered by the Board unless and until the
Board delegates administration to a committee, as provided in Article II,
paragraph 2(c).

      (b)   The Board shall have the power, subject to, and within the
limitations of, the express provisions of the Plan:

            (1)   To determine from time to time which of the persons eligible
under the Plan shall be granted Stock Awards; when and how Stock Awards shall be
granted; whether a Stock Award will be an Incentive Stock Option, a Nonqualified
Stock Option, a stock bonus, a right to purchase restricted stock, or a
combination of the foregoing; the provisions of each Stock Award granted (which
need not be identical), including the time or times when a person shall be
permitted to purchase or receive stock pursuant to a Stock Award; and the number
of shares with respect to which Stock Awards shall be granted to each such
person.

            (2)   To construe and interpret the Plan and Stock Awards granted
under it, and to establish, amend and revoke rules and regulations for its
administration. The Board, in the exercise of this power, may correct any
defect, omission or inconsistency in the Plan or in any

                                       17



Stock Award, in a manner and to the extent it shall deem necessary or expedient
to make the Plan fully effective.

            (3)   To amend the Plan as provided in Article II, Section 14.

            (4)   Generally, to exercise such powers and to perform such acts as
the Board deems necessary or expedient to promote the best interests of the
Company.

      (c)   The Board may delegate administration of the Plan to a committee
composed of not fewer than two (2) members of the Board (the "Committee"). One
or more of these members may be non-employee directors and outside directors, if
required and as defined by the provisions of Article II, paragraphs 2(e) and
2(f). If administration is delegated to a Committee, the Committee shall have,
in connection with the administration of the Plan, the powers theretofore
possessed by the Board (except amendment of any program adopted pursuant to
Article II, Section 6 or any Non-Discretionary Director Awards granted
thereunder shall only be by action taken by the Board or a committee of one or
more members of the Board to which such authority has been specifically
delegated by the Board), subject, however, to such resolutions, not inconsistent
with the provisions of Article II of the Plan, as may be adopted from time to
time by the Board. Notwithstanding anything else in this Article II, paragraph
2(c) to the contrary, at any time the Board or the Committee may delegate to a
committee of one or more members of the Board the authority to grant or amend
options to all employees, directors or consultants or any portion or class
thereof.

      (d)   Notwithstanding anything else in the Plan to the contrary, at any
time the Board or the Committee may authorize by duly adopted resolution one or
more Officers (as defined below) (each a "Delegated Officer") to take the
actions described in Article II, paragraph 2(b)(1) of the Plan with respect to
Options only, subject to, and within the limitations of, the express provisions
of Article II of the Plan; provided, however, that a Delegated Officer shall not
have the power to (1) grant any Options to himself, any non-employee director,
consultant, Trust, other Delegated Officer or Officer, (2) determine the time or
times when a person shall be permitted to purchase stock pursuant to the
exercise of an Option (i.e., vesting), (3) determine the exercise price of an
Option, or (4) grant any Option to a parent corporation of the Company, as
defined in Section 424(e) of the Code. The resolution authorizing a Delegated
Officer to act as such shall specify the total number of shares of Common Stock
that a Delegated Officer may grant with respect to Options. The exercise price
(including any

                                       18



formula by which such price or prices may be determined) and the time or times
when a person shall be permitted to purchase stock pursuant to the exercise of
an Option shall, however, be set by the Board or the Committee and not by a
Delegated Officer to the extent required by Delaware General Corporation Law
Section 157 or any other applicable law. The term "Officer" shall include any
natural person who is elected as a corporate officer of the Company by the
Board.

      (e)  The term "non-employee director" shall mean a member of the Board who
(i) is not currently an officer of the Company or a parent or subsidiary of the
Company (as defined in Rule 16a-1(f) promulgated by the Securities and Exchange
Commission under Section 16 of the Securities Exchange Act of 1934, as amended
(the "Exchange Act")) or an employee of the Company or a parent or subsidiary of
the Company; (ii) does not receive compensation from the Company or a parent or
subsidiary of the Company for services rendered in any capacity other than as a
member of the Board (including a consultant) in an amount required to be
disclosed to the Company's stockholders under Rule 404 of Regulation S-K
promulgated by the Securities and Exchange Commission ("Rule 404"); (iii) does
not possess an interest in any other transaction required to be disclosed under
Rule 404; or (iv) is not engaged in a business relationship required to be
disclosed under Rule 404, as all of these provisions are interpreted by the
Securities and Exchange Commission under Rule 16b-3 promulgated under the
Exchange Act.

      (f)  The term "outside director," as used in Article II of this Plan,
shall mean an administrator of the Plan, whether a member of the Board or of any
Committee to which responsibility for administration of the Plan has been
delegated pursuant to Article II, paragraph 2(c), who is considered to be an
"outside director" in accordance with the rules, regulations or interpretations
of Section 162(m) of the Code.

      (g)  Any requirement that an administrator of the Plan be a "non-employee
director" or "outside director" shall not apply if the Board or the Committee
expressly declares that such requirement shall not apply.

SECTION 3. SHARES SUBJECT TO THE PLAN.

      (a)  Subject to the provisions of Article II, Section 11 relating to
adjustments upon changes in stock, the stock that may be issued pursuant to
Stock Awards granted under the Plan

                                       19



shall not exceed in the aggregate 19,510,646 shares of the Company's $.0001 par
value common stock (the "Common Stock"). If any Stock Award granted under the
Plan shall for any reason expire or otherwise terminate without having been
exercised in full, the Common Stock not purchased under such Stock Award shall
again become available for the Plan. Shares repurchased by the Company pursuant
to any repurchase rights reserved by the Company pursuant to the Plan shall not
be available for subsequent issuance under the Plan.

      (b)  The Common Stock subject to the Plan may be unissued shares or
reacquired shares, bought on the market or otherwise.

      (c)  An Incentive Stock Option may be granted to an eligible person under
the Plan only if the aggregate fair market value (determined at the time the
Incentive Stock Option is granted) of the Common Stock with respect to which
incentive stock options (as defined by the Code) are exercisable for the first
time by such optionee during any calendar year under all such plans of the
Company and its Affiliates does not exceed one hundred thousand dollars
($100,000). If it is determined that an entire Option or any portion thereof
does not qualify for treatment as an Incentive Stock Option by reason of
exceeding such maximum, such Option or the applicable portion shall be
considered a Nonqualified Stock Option.

SECTION 4. ELIGIBILITY.

      (a)  Incentive Stock Options may be granted only to employees (including
officers) of the Company or its Affiliates. A director of the Company shall not
be eligible to receive Incentive Stock Options unless such director is also an
employee of the Company or any Affiliate. Stock Awards other than Incentive
Stock Options may be granted to employees (including officers) or directors of
or consultants to the Company or any Affiliate or to Trusts of any such
employee, director or consultant.

      (b)  A director shall in no event be eligible for the benefits of the Plan
(other than Non-Discretionary Director Awards, as defined in Article II, Section
6) unless and until such director is expressly declared eligible to participate
in the Plan by action of the Board or the Committee, and only if, at any time
discretion is exercised by the Board or the Committee in the selection of a
director as a person to whom Stock Awards may be granted, or in the
determination of the number of shares which may be covered by Stock Awards
granted to a director, the Plan complies with the requirements of Rule 16b-3
promulgated under the Exchange Act, as from

                                       20



time to time in effect. The Board shall otherwise comply with the requirements
of Rule 16b-3 promulgated under the Exchange Act, as from time to time in
effect. Notwithstanding the foregoing, the restrictions set forth in this
Article II, paragraph 4(b) shall not apply if the Board or Committee expressly
declares that such restrictions shall not apply.

      (c)  No person shall be eligible for the grant of an Incentive Stock
Option under the Plan if, at the time of grant, such person owns (or is deemed
to own pursuant to Section 424(d) of the Code) stock possessing more than ten
percent (10%) of the total combined voting power of all classes of stock of the
Company or of any of its Affiliates unless the exercise price of such Incentive
Stock Option is at least one hundred and ten percent (110%) of the fair market
value of the Common Stock at the date of grant and the Incentive Stock Option is
not exercisable after the expiration of five (5) years from the date of grant.

      (d)  Stock Awards shall be limited to a maximum of 1,298,311 shares of
Common Stock per person per calendar year.

SECTION 5. TERMS OF DISCRETIONARY STOCK OPTIONS.

      An option granted pursuant to this Article II, Section 5 (a "Discretionary
Stock Option") shall be in such form and shall contain such terms and conditions
as the Board or the Committee shall deem appropriate. The provisions of separate
Options need not be identical, but each Option shall include (through
incorporation of provisions hereof by reference in the Option or otherwise) the
substance of each of the following provisions:

      (a)  No Option shall be exercisable after the expiration of ten (10) years
from the date it was granted.

      (b)  The exercise price of each Incentive Stock Option and each
Nonqualified Stock Option shall be not less than one hundred percent (100%) of
the fair market value of the Common Stock subject to the Option on the date the
Option is granted.

      (c)  The purchase price of Common Stock acquired pursuant to an Option
shall be paid, to the extent permitted by applicable statutes and regulations,
either: (i) in cash at the time the Option is exercised; or (ii) at the
discretion of the Board or the Committee, either at the time of grant or
exercise of the Option (A) by delivery to the Company of shares of Common Stock

                                       21



that have been held for the period required to avoid a charge to the Company's
reported earnings and valued at the fair market value on the date of exercise,
(B) according to a deferred payment or other arrangement with the person to whom
the Option is granted or to whom the Option is transferred pursuant to Article
II, paragraph 5(d), or (C) in any other form of legal consideration that may be
acceptable to the Board or the Committee in their discretion; including but not
limited to payment of the purchase price pursuant to a program developed under
Regulation T as promulgated by the Federal Reserve Board which results in the
receipt of cash (or a check) by the Company before Common Stock is issued or the
receipt of irrevocable instruction to pay the aggregate exercise price to the
Company from the sales proceeds before Common Stock is issued.

      In the case of any deferred payment arrangement, interest shall be payable
at least annually and shall be charged at not less than the minimum rate of
interest necessary to avoid the treatment as interest, under any applicable
provisions of the Code, of any amounts other than amounts stated to be interest
under the deferred payment arrangement.

      (d)  An Option granted to a natural person shall be exercisable during the
lifetime of such person only by such person, provided that such person during
such person's lifetime may designate a Trust to be such person's beneficiary
with respect to any Incentive Stock Options and with respect to any Nonqualified
Stock Options, and such beneficiary shall, after the death of the person to whom
the Option was granted, have all the rights that such person has while living,
including the right to exercise the Option. In the absence of such designation,
after the death of the person to whom the Option is granted, the Option shall be
exercisable by the person or persons to whom the optionee's rights under such
Option pass by will or by the laws of descent and distribution.

      (e)  The total number of shares of Common Stock subject to an Option may,
but need not, be allotted in periodic installments (which may, but need not, be
equal). From time to time during each of such installment periods, the Option
may become exercisable ("vest") with respect to some or all of the shares
allotted to that period, and may be exercised with respect to some or all of the
shares allotted to such period and/or any prior period as to which the Option
was not fully exercised. During the remainder of the term of the Option (if its
term extends beyond the end of the installment periods), the Option may be
exercised from time to time with respect to any shares then remaining subject to
the Option. The provisions of this Article II, paragraph 5(e) are subject to any
Option provisions governing the minimum number of shares

                                       22



as to which an Option may be exercised.

      (f)  The Company may require any optionee, or any person to whom an Option
is transferred under Article II, paragraph 5(d), as a condition of exercising
any such Option: (i) to give written assurances satisfactory to the Company as
to such person's knowledge and experience in financial and business matters
and/or to employ a purchaser representative who has such knowledge and
experience in financial and business matters, and that such person is capable of
evaluating, alone or together with the purchaser representative, the merits and
risks of exercising the Option; and (ii) to give written assurances satisfactory
to the Company stating that such person is acquiring the Common Stock subject to
the Option for such person's own account and not with any present intention of
selling or otherwise distributing the Common Stock. These requirements, and any
assurances given pursuant to such requirements, shall be inoperative if: (x) the
issuance of the shares upon the exercise of the Option has been registered under
a then currently effective registration statement under the Securities Act of
1933, as amended (the "Securities Act"); or (y) as to any particular
requirement, a determination is made by counsel for the Company that such
requirement need not be met in the circumstances under the then applicable
securities law.

      (g)  An Option shall terminate three (3) months after termination of the
optionee's employment or relationship as a consultant or director with the
Company or an Affiliate, unless: (i) such termination is due to the optionee's
permanent and total disability, within the meaning of Section 422(c)(6) of the
Code and with such permanent and total disability being certified by the Social
Security Administration prior to such termination, in which case the Option may,
but need not, provide that it may be exercised at any time within one (1) year
following such termination of employment or relationship as a consultant or
director; (ii) the optionee dies while in the employ of or while serving as a
consultant or director to the Company or an Affiliate, or within not more than
three (3) months after termination of such employment or relationship as a
consultant or director, in which case the Option may, but need not, provide that
it may be exercised at any time within eighteen (18) months following the death
of the optionee by the person or persons to whom the optionee's rights under
such Option pass by will or by the laws of descent and distribution; or (iii)
the Option by its term specifies either (A) that it shall terminate sooner than
three (3) months after termination of the optionee's employment or relationship
as a consultant or director with the Company or an Affiliate; or (B) that it may
be exercised more than three (3) months after termination of the optionee's
employment or relationship as a consultant or director with the Company or an
Affiliate. This Article II,

                                       23



paragraph 5(g) shall not be construed to extend the term of any Option or to
permit anyone to exercise the Option after expiration of its term, nor shall it
be construed to increase the number of shares as to which any Option is
exercisable from the amount exercisable on the date of termination of the
optionee's employment or relationship as a consultant or director.

      (h)  The Option may, but need not, include a provision whereby the
optionee may elect at any time during the term of the optionee's employment or
relationship as a consultant or director with the Company or any Affiliate to
exercise the Option as to any part or all of the shares subject to the Option
prior to the stated vesting dates of the Option. Any shares so purchased from
any unvested installment or Option may be subject to a repurchase right in favor
of the Company or to any other restriction the Board or the Committee determines
to be appropriate.

      (i)  To the extent provided by the terms of an Option, each optionee may
satisfy any federal, state or local tax withholding obligation relating to the
exercise of such Option by any of the following means or by a combination of
such means: (i) tendering a cash payment; (ii) authorizing the Company to
withhold from the shares of the Common Stock otherwise issuable to the optionee
as a result of the exercise of the Option a number of shares having a fair
market value less than or equal to the amount of the Company's required minimum
statutory withholding; or (iii) delivering to the Company owned and unencumbered
shares of the Common Stock having a fair market value less than or equal to the
amount of the Company's required minimum statutory withholding.

SECTION 6. NON-DISCRETIONARY DIRECTOR AWARDS.

      The Board may from time to time adopt award programs under the Plan
providing for the grant of formula or non-discretionary Stock Awards to
directors of the Company who are not employees of the Company or any Affiliate
("Non-Discretionary Director Awards"). The terms and conditions of any such
program shall be established by the Board in its sole discretion, subject to the
terms and conditions of the Plan.

SECTION 7. TERMS OF STOCK BONUSES AND PURCHASES OF RESTRICTED STOCK.

      Each stock bonus or restricted stock purchase agreement shall be in such
form and shall

                                       24



contain such terms and conditions as the Board or the Committee shall deem
appropriate. The terms and conditions of stock bonus or restricted stock
purchase agreements may change from time to time, and the terms and conditions
of separate agreements need not be identical, but each stock bonus or restricted
stock purchase agreement shall include (through incorporation of provisions
hereof by reference in the agreement or otherwise) the substance of each of the
following provisions as appropriate:

      (a)  The purchase price under each stock purchase agreement shall be such
amount as the Board or Committee shall determine and designate in such
agreement. Notwithstanding the foregoing, the Board or the Committee may
determine that eligible participants in the Plan may be awarded stock pursuant
to a stock bonus agreement in consideration for past services actually rendered
to the Company or for its benefit.

      (b)  No rights under a stock bonus or restricted stock purchase agreement
shall be assignable by any participant under the Plan, either voluntarily or by
operation of law, except where such assignment is required by law or expressly
authorized by the terms of the applicable stock bonus or restricted stock
purchase agreement.

      (c)  The purchase price of stock acquired pursuant to a stock purchase
agreement shall be paid either: (i) in cash at the time of purchase; (ii) at the
discretion of the Board or the Committee, according to a deferred payment or
other arrangement with the person to whom the Common Stock is sold; or (iii) in
any other form of legal consideration that may be acceptable to the Board or the
Committee in their discretion; including but not limited to payment of the
purchase price pursuant to a program developed under Regulation T as promulgated
by the Federal Reserve Board which results in the receipt of cash (or a check)
by the Company before Common Stock is issued or the receipt of irrevocable
instruction to pay the aggregate exercise price of the Company from the sales
proceeds before Common Stock is issued. Notwithstanding the foregoing, the Board
or the Committee to which administration of the Plan has been delegated may
award Common Stock pursuant to a stock bonus agreement in consideration for past
services actually rendered to the Company or for its benefit.

      (d)  Shares of Common Stock sold or awarded under the Plan may, but need
not, be subject to a repurchase option in favor of the Company in accordance
with a vesting schedule to be determined by the Board or the Committee.

                                       25



      (e)  In the event a person ceases to be an employee of or ceases to serve
as a director or consultant to the Company or an Affiliate, the Company may
repurchase or otherwise reacquire any or all of the shares of Common Stock held
by that person which have not vested as of the date of termination under the
terms of the stock bonus or restricted stock purchase agreement between the
Company and such person.

      (f)  To the extent provided by the terms of a stock bonus or restricted
stock purchase agreement, a participant may satisfy any federal, state or local
tax withholding obligation relating to the lapsing of a repurchase option in
favor of the Company or vesting of a stock bonus or a restricted stock award by
any of the following means or by a combination of such means: (i) tendering a
cash payment; (ii) authorizing the Company to withhold from the shares of the
Common Stock otherwise deliverable to a participant as a result of the lapsing
of a repurchase option in favor of the Company or the vesting of a stock bonus
or a restricted stock award a number of shares having a fair market value less
than or equal to the amount of the Company's required minimum statutory
withholding; or (iii) delivering to the Company owned and unencumbered shares of
the Common Stock having a fair market value less than or equal to the amount of
the Company's required minimum statutory withholding.

SECTION 8. COVENANTS OF THE COMPANY.

      (a)  During the terms of the Stock Awards granted under the Plan, the
Company shall keep available at all times the number of shares of Common Stock
required to satisfy such Stock Awards up to the number of shares of Common Stock
authorized under the Plan.

      (b)  The Company shall seek to obtain from each regulatory commission or
agency having jurisdiction over the Plan such authority as may be required to
issue and sell shares of Common Stock under the Stock Awards granted under the
Plan; provided, however, that this undertaking shall not require the Company to
register under the Securities Act either the Plan, any Stock Award granted under
the Plan or any Common Stock issued or issuable pursuant to any such Stock
Award. If, after reasonable efforts, the Company is unable to obtain from any
such regulatory commission or agency the authority that counsel for the Company
deems necessary for the lawful issuance and sale of Common Stock under the Plan,
the Company shall be relieved from any liability for failure to issue and sell
Common Stock upon exercise of such Stock Awards unless and until such authority
is obtained.

                                       26



SECTION 9. USE OF PROCEEDS FROM COMMON STOCK.

      Proceeds from the sale of Common Stock pursuant to Stock Awards granted
under the Plan shall constitute general funds of the Company.

SECTION 10. MISCELLANEOUS.

      (a)  The Board or Committee shall have the power to accelerate the time
during which a Stock Award may be exercised or the time during which a Stock
Award or any part thereof will vest, notwithstanding the provisions in the Stock
Award stating the time during which it may be exercised or the time during which
it will vest. Each Discretionary Stock Option providing for vesting pursuant to
Article II, paragraph 5(e) shall also provide that if the employee's employment
or a director's or consultant's affiliation with the Company or an Affiliate of
the Company is terminated by reason of death or disability (within the meaning
of Title II or XVI of the Social Security Act or comparable statute applicable
to an Affiliate and with such permanent and total disability certified by (i)
the Social Security Administration, (ii) the comparable governmental authority
applicable to an Affiliate, (iii) such other body having the relevant
decision-making power applicable to an Affiliate or (iv) an independent medical
advisor appointed by the Company, as applicable, prior to such termination),
then the vesting schedule of Discretionary Stock Options granted to such
employee, director or consultant or to the Trusts of such employee, director or
consultant shall be accelerated by twelve months for each full year the employee
has been employed by or the director or consultant has been affiliated with the
Company and/or an Affiliate of the Company.

      (b)  Neither an optionee nor any person to whom an Option is transferred
under the provisions of the Plan shall be deemed to be the holder of, or to have
any of the rights of a holder with respect to, any shares subject to such Option
unless and until such person has satisfied all requirements for exercise of the
Option pursuant to its terms.

      (c)  Nothing in the Plan or any instrument executed or Stock Award granted
pursuant thereto shall confer upon any eligible employee, consultant, director,
optionee or holder of Stock Awards under the Plan any right to continue in the
employ of the Company or any Affiliate or to continue acting as a consultant or
director or shall affect the right of the Company or any Affiliate to terminate
the employment or consulting relationship or directorship of any eligible
employee, consultant, director, optionee or holder of Stock Awards under the
Plan with

                                       27



or without cause. In the event that a holder of Stock Awards under the Plan is
permitted or otherwise entitled to take a leave of absence, the Company shall
have the unilateral right to (i) determine whether such leave of absence will be
treated as a termination of employment or relationship as consultant or director
for purposes hereof, and (ii) suspend or otherwise delay the time or times at
which exercisability or vesting would otherwise occur with respect to any
outstanding Stock Awards under the Plan.

SECTION 11. ADJUSTMENTS UPON CHANGES IN COMMON STOCK.

      If any change is made in the Common Stock subject to the Plan, or subject
to any Stock Award granted under the Plan (through merger, consolidation,
reorganization, recapitalization, stock dividend, dividend in property other
than cash, stock split, liquidating dividend, combination of shares, exchange of
shares, change in corporate structure or other transaction not involving the
receipt of consideration by the Company), the Plan and outstanding Stock Awards
will be appropriately adjusted in the class(es) and maximum number of shares
subject to the Plan, the maximum number of shares which may be granted to a
participant in a calendar year, the class(es) and number of shares and price per
share of stock subject to outstanding Stock Awards, and the number of shares of
Common Stock to be granted as Non-Discretionary Director Awards, if any. Such
adjustment shall be made by the Board or the Committee, the determination of
which shall be final, binding and conclusive. (The conversion of any convertible
securities of the Company shall not be treated as a "transaction not involving
the receipt of consideration".)

SECTION 12. CHANGE OF CONTROL.

      (a)  Notwithstanding anything to the contrary in this Plan, in the event
of a Change in Control (as hereinafter defined), then, to the extent permitted
by applicable law: (i) the time during which Stock Awards become vested shall
automatically be accelerated so that the unvested portions of all Stock Awards
shall be vested prior to the Change in Control and (ii) the time during which
the Options may be exercised shall automatically be accelerated to prior to the
Change in Control. Upon and following the acceleration of the vesting and
exercise periods, at the election of the holder of the Stock Award, the Stock
Award may be: (x) exercised (with respect to Options) or, if the surviving or
acquiring corporation agrees to assume the Stock Awards or substitute similar
stock awards, (y) assumed; or (z) replaced with substitute stock awards. Options
not exercised, substituted or assumed prior to or upon the

                                       28



Change in Control shall be terminated.

      (b)  For purposes of Article II of the Plan, a "Change of Control" shall
be deemed to have occurred at any of the following times:

           (i)   upon the acquisition (other than from the Company) by any
person, entity or "group," within the meaning of Section 13(d)(3) or 14(d)(2) of
the Exchange Act (excluding, for this purpose, the Company or its affiliates, or
any employee benefit plan of the Company or its affiliates which acquires
beneficial ownership of voting securities of the Company), of beneficial
ownership (within the meaning of Rule 13d-3 promulgated under the Exchange Act)
of fifty percent (50%) or more of either the then outstanding shares of Common
Stock or the combined voting power of the Company's then outstanding voting
securities entitled to vote generally in the election of directors; or

           (ii)  at the time individuals who, as of July 15, 2002, constitute
the Board (the "Incumbent Board") cease for any reason to constitute at least a
majority of the Board, provided that any person becoming a director subsequent
to July 15, 2002, whose election, or nomination for election by the Company's
stockholders, was approved by a vote of at least a majority of the directors
then comprising the Incumbent Board (other than an election or nomination of an
individual whose initial assumption of office is in connection with an actual or
threatened election contest relating to the election of the Directors of the
Company, as such terms are used in Rule 14a-11 of Regulation 14A promulgated
under the Exchange Act) shall be, for purposes of Article II of the Plan,
considered as though such person were a member of the Incumbent Board; or

           (iii) immediately prior to the consummation by the Company of a
reorganization, merger, consolidation, (in each case, with respect to which
persons who were the stockholders of the Company immediately prior to such
reorganization, merger or consolidation do not, immediately thereafter, own more
than fifty percent (50%) of the combined voting power entitled to vote generally
in the election of directors of the reorganized, merged or consolidated
company's then outstanding voting securities) or a liquidation or dissolution of
the Company or of the sale of all or substantially all of the assets of the
Company; or

           (iv)  the occurrence of any other event which the Incumbent Board in
its sole

                                       29



discretion determines constitutes a Change of Control.

SECTION 13. QUALIFIED DOMESTIC RELATIONS ORDERS

      (a)  Anything in the Plan to the contrary notwithstanding, rights under
Stock Awards may be assigned to an Alternate Payee to the extent that a QDRO so
provides. (The terms "Alternate Payee" and "QDRO" are defined in Article II,
paragraph 13(c) below.) The assignment of a Stock Award to an Alternate Payee
pursuant to a QDRO shall not be treated as having caused a new grant. The
transfer of an Incentive Stock Option to an Alternate Payee may, however, cause
it to fail to qualify as an Incentive Stock Option. If a Stock Award is assigned
to an Alternate Payee, the Alternate Payee generally has the same rights as the
grantee under the terms of the Plan; provided however, that (i) the Stock Award
shall be subject to the same vesting terms and exercise period as if the Stock
Award were still held by the grantee and (ii) an Alternate Payee may not
transfer a Stock Award.

      (b)  In the event of the Plan administrator's receipt of a domestic
relations order or other notice of adverse claim by an Alternate Payee of a
grantee of a Stock Award, transfer of the proceeds of the exercise of such Stock
Award, whether in the form of cash, stock or other property, may be suspended.
Such proceeds shall thereafter be transferred pursuant to the terms of a QDRO or
other agreement between the grantee and Alternate Payee. A grantee's ability to
exercise a Stock Award may be barred if the Plan administrator receives a court
order directing the Plan administrator not to permit exercise.

      (c)  The word "QDRO" as used in Article II of the Plan shall mean a court
order (i) that creates or recognizes the right of the spouse, former spouse or
child (an "Alternate Payee") of an individual who is granted a Stock Award to an
interest in such Stock Award relating to marital property rights or support
obligations and (ii) that the administrator of the Plan determines would be a
"qualified domestic relations order," as that term is defined in section 414(p)
of the Code and section 206(d) of the Employee Retirement Income Security Act
("ERISA"), but for the fact that the Plan is not a plan described in section
3(3) of ERISA.

SECTION 14. AMENDMENT OF THE PLAN.

      (a)  The Board at any time, and from time to time, may amend the Plan.
However, except as provided in Article II, Section 11 relating to adjustments
upon changes in the

                                       30



Common Stock, no amendment shall be effective unless approved by the
stockholders of the Company within twelve (12) months before or after the
adoption of the amendment, where the amendment will:

           (i)   increase the number of shares reserved for Stock Awards under
the Plan;

           (ii)  modify the requirements as to eligibility for participation in
the Plan (to the extent such modification requires stockholder approval in order
for the Plan to satisfy the requirements of Section 422(b) of the Code); or

           (iii) modify the Plan in any other way if such modification requires
stockholder approval in order for the Plan to satisfy the requirements of
Section 422(b) of the Code.

      (b)  The Board may in its sole discretion submit any other amendment to
the Plan for stockholder approval, including, but not limited to, amendments to
the Plan intended to satisfy the requirements of Section 162(m) of the Code and
the regulations promulgated thereunder regarding the exclusion of
performance-based compensation from the limit on corporate deductibility of
compensation to certain executive officers.

      (c)  It is expressly contemplated that the Board may amend the Plan in any
respect the Board deems necessary or advisable to provide optionees with the
maximum benefits provided or to be provided under the provisions of the Code and
the regulations promulgated thereunder relating to employee Incentive Stock
Options and/or to bring the Plan and/or Options granted under it into compliance
therewith.

      (d)  Rights and obligations under any Stock Award granted before amendment
of the Plan shall not be impaired by any amendment of the Plan, unless: (i) the
Company requests the consent of the person to whom the Stock Award was granted;
and (ii) such person consents in writing.

SECTION 15. TERMINATION OR SUSPENSION OF THE PLAN.

      (a)  The Board may suspend or terminate the Plan at any time. No Stock
Awards may be granted under the Plan while the Plan is suspended or after it is
terminated. No

                                       31



Incentive Stock Options may be granted under the Plan after March 10, 2003.

      (b)  Rights and obligations under any Stock Awards granted while the Plan
is in effect shall not be impaired by suspension or termination of the Plan,
except with the consent of the person to whom the Stock Award was granted.

      (c)  Unless sooner terminated by the Board, the Plan shall automatically
terminate on March 11, 2003 (which is the tenth anniversary of the date on which
the Board of Directors of Immunex Corporation first adopted the Original Plan).
No Stock Awards may be granted under the Plan after such termination.

                                       32

                                                                    EXHIBIT 10.2

                                   AMGEN INC.

                 AMENDED AND RESTATED 1999 EQUITY INCENTIVE PLAN

     Amgen Inc. has adopted this Amended and Restated 1999 Equity Incentive Plan
(the "Plan"), effective as of July 15, 2002 (the "Restatement Date"). This Plan
amends and restates in its entirety the Immunex Corporation 1999 Stock Option
Plan, as amended (the "Original Plan").

                                   ARTICLE I.

                    PROVISIONS APPLICABLE TO OPTIONS GRANTED
                            PRIOR TO RESTATEMENT DATE

     The following provisions of this Article I shall govern awards granted
under the Plan prior to the Restatement Date:

SECTION 1. PURPOSE.

     The purpose of Article I of the Plan is to enhance the long-term
stockholder value of Amgen Inc., a Delaware corporation (the "Company"), by
offering opportunities to selected employees, officers and directors to
participate in the Company's growth and success, and to encourage them to remain
in the service of the Company and its Related Corporations (as defined in
Article I, Section 2) and to acquire and maintain stock ownership in the
Company.

SECTION 2. DEFINITIONS.

     For purposes of the Plan, the following terms shall be defined as set forth
below:

     "Board" means the Board of Directors of the Company.

     "Cause" means dishonesty, fraud, misconduct, unauthorized use or disclosure
of confidential information or trade secrets, or conviction or confession of a
crime punishable by law (except minor violations), in each case as determined by
the Plan Administrator, and its determination shall be conclusive and binding.



     "Code" means the Internal Revenue Code of 1986, as amended from time to
time.

     "Common Stock" means the common stock, par value $.0001 per share, of the
Company.

     "Disability," unless otherwise defined by the Plan Administrator, means a
mental or physical impairment of the Optionee that is expected to result in
death or that has lasted or is expected to last for a continuous period of 12
months or more and that causes the Optionee to be unable, in the opinion of the
Company and one independent physician selected by the Company, to perform his or
her duties for the Company or a Related Corporation and to be engaged in any
substantial gainful activity.

     "Effective Date" means the date on which the Plan was adopted by the Board
of Directors of Immunex Corporation ("Immunex"), provided that it was approved
by Immunex's stockholders at any time within 12 months of such adoption.

     "Exchange Act" means the Securities Exchange Act of 1934, as amended.

     "Exchange Stock" has the meaning set forth in Article I, Section 11.3.

     "Fair Market Value" shall be as established in good faith by the Plan
Administrator or (a) if the Common Stock is listed on the Nasdaq National
Market, the closing per share sales prices for the Common Stock as reported by
the Nasdaq National Market for a single trading day or (b) if the Common Stock
is listed on the New York Stock Exchange or the American Stock Exchange, the
closing per share sales prices for the Common Stock as such price is officially
quoted in the composite tape of transactions on such exchange for a single
trading day. If there is no such reported price for the Common Stock for the
date in question, then such price on the last preceding date for which such
price exists shall be determinative of Fair Market Value.

     "Grant Date" means the date on which the Plan Administrator completes the
corporate action relating to the grant of an Option and all conditions precedent
to the grant have been satisfied, provided that conditions to the exercisability
or vesting of Options shall not defer the Grant Date.

                                       2



     "Incentive Stock Option" means an Option to purchase Common Stock granted
under Article I, Section 7 with the intention that it qualify as an "incentive
stock option" as that term is defined in Section 422 of the Code.

     "Nonqualified Stock Option" means an Option to purchase Common Stock
granted under Article I, Section 7 other than an Incentive Stock Option.

     "Option" means the right to purchase Common Stock granted under Article I,
Section 7.

     "Optionee" means (a) the person to whom an Option is granted; (b) for an
Optionee who has died, the personal representative of the Optionee's estate, the
person(s) to whom the Optionee's rights under the Option have passed by will or
by the applicable laws of descent and distribution, or the beneficiary
designated in accordance with Article I, Section 10; or (c) the person(s) to
whom an Option has been transferred in accordance with Article I, Section 10.

     "Option Term" has the meaning set forth in Article I, Section 7.3.

     "Parent," except as provided in Article I, Section 8.3 in connection with
Incentive Stock Options, means any entity, whether now or hereafter existing,
that directly or indirectly controls the Company.

     "Plan Administrator" means the Board or any committee or committees
designated by the Board or any person to whom the Board has delegated authority
to administer the Plan under Article I, Section 3.1.

     "Related Corporation" means any Parent or Subsidiary of the Company.

     "Retirement" means retirement as of the individual's normal retirement date
under the Amgen Inc. Profit Sharing 401(k) Plan and Trust or other similar
successor plan applicable to salaried employees, unless otherwise defined by the
Plan Administrator from time to time for purposes of Article I of the Plan.

     "Securities Act" means the Securities Act of 1933, as amended.

     "Subsidiary," except as provided in Article I, Section 8.3 in connection
with Incentive Stock Options, means any entity that is directly or indirectly
controlled by the Company.

                                       3



     "Termination Date" has the meaning set forth in Article I, Section 7.6.

SECTION 3.  ADMINISTRATION.

     3.1  Plan Administrator.

     The Plan shall be administered by the Board and/or a committee or
committees (which term includes subcommittees) appointed by, and consisting of
two or more members of, the Board (a "Plan Administrator"). If and so long as
the Common Stock is registered under Section 12(b) or 12(g) of the Exchange Act,
the Board shall consider in selecting the members of any committee acting as
Plan Administrator, with respect to any persons subject or likely to become
subject to Section 16 of the Exchange Act, the provisions regarding (a) "outside
directors" as contemplated by Section 162(m) of the Code and (b) "nonemployee
directors" as contemplated by Rule 16b-3 under the Exchange Act. The Board may
delegate the responsibility for administering the Plan with respect to
designated classes of eligible persons to different committees consisting of two
or more members of the Board, subject to such limitations as the Board deems
appropriate. Committee members shall serve for such term as the Board may
determine, subject to removal by the Board at any time. To the extent consistent
with applicable law, the Board may authorize one or more senior executive
officers of the Company to grant Options to specified eligible persons, within
the limits specifically prescribed by the Board.

     3.2  Administration and Interpretation by Plan Administrator.

     Except for the terms and conditions explicitly set forth in the Plan, the
Plan Administrator shall have exclusive authority, in its discretion, to
determine all matters relating to Options under the Plan, including the
selection of individuals to be granted Options, the type of Options, the number
of shares of Common Stock subject to an Option, all terms, conditions,
restrictions and limitations, if any, of an Option and the terms of any
instrument that evidences the Option. The Plan Administrator shall also have
exclusive authority to interpret the Plan and may from time to time adopt, and
change, rules and regulations of general application for the Plan's
administration. The Plan Administrator's interpretation of the Plan and its
rules and regulations, and all actions taken and determinations made by the Plan
Administrator pursuant to the Plan, shall be conclusive and binding on all
parties involved or affected. The Plan

                                       4



Administrator may delegate administrative duties to such of the Company's
officers as it so determines.

SECTION 4.  STOCK SUBJECT TO THE PLAN.

     4.1  Shares Available for Issuance.

     Subject to adjustment from time to time as provided in Article I, Section
11.1, shares of Common Stock shall be available for issuance under the Plan.
Shares issued under the Plan shall be drawn from authorized and unissued shares
or shares now held or subsequently acquired by the Company.

     4.2  Reuse of Shares.

     Any shares of Common Stock that have been made subject to an Option that
cease to be subject to the Option (other than by reason of exercise of the
Option to the extent it is exercised for shares) shall again be available for
issuance in connection with future grants of Options under the Plan; provided,
however, that for purposes of any individual award limit under the Plan, any
such shares shall be counted in accordance with the requirements of Section
162(m) of the Code.

SECTION 5.  ELIGIBILITY.

     Options may be granted under the Plan to those officers, directors and
employees of the Company and its Related Corporations as the Plan Administrator
from time to time selects.

SECTION 6.  ACQUIRED COMPANY OPTIONS.

     Notwithstanding anything in the Plan to the contrary, the Plan
Administrator may grant Options under the Plan in substitution for awards issued
under other plans, or assume under the Plan awards issued under other plans, if
the other plans are or were plans of other acquired entities ("Acquired
Entities") (or the parent of the Acquired Entity) and the new Option is
substituted, or the old option is assumed, by reason of a merger, consolidation,
acquisition of property or of stock, reorganization or liquidation (the
"Acquisition Transaction"). In the event that a written agreement pursuant to
which the Acquisition Transaction is completed is approved by the Board and said
agreement sets forth the terms and conditions of the

                                       5



substitution for or assumption of outstanding options of the Acquired Entity,
said terms and conditions shall be deemed to be the action of the Plan
Administrator without any further action by the Plan Administrator, except as
may be required for compliance with Rule 16b-3 under the Exchange Act, and the
persons holding such awards shall be deemed to be Optionees.

SECTION 7.  TERMS AND CONDITIONS OF OPTIONS.

     7.1  Grant of Options.

     The Plan Administrator is authorized under the Plan, in its sole
discretion, to issue Options as Incentive Stock Options or as Nonqualified Stock
Options, which shall be appropriately designated.

     7.2  Option Exercise Price.

     The exercise price for shares purchased under an Option shall be as
determined by the Plan Administrator, but shall not be less than 100% of the
Fair Market Value of the Common Stock on the Grant Date with respect to
Incentive Stock Options and not less than 85% of the Fair Market Value of the
Common Stock on the Grant Date with respect to Nonqualified Stock Options. For
Incentive Stock Options granted to a more than 10% stockholder, the Option
exercise price shall be as specified in Article I, Section 8.2.

     7.3  Term of Options.

     The term of each Option (the "Option Term") shall be as established by the
Plan Administrator or, if not so established, shall be 10 years from the Grant
Date. For Incentive Stock Options, the maximum Option Term shall be as specified
in Article I, Sections 8.2 and 8.4.

     7.4  Exercise of Options.

     The Plan Administrator shall establish and set forth in each instrument
that evidences an Option the time at which, or the installments in which, the
Option shall vest and become exercisable, which provisions may be waived or
modified by the Plan Administrator at any time. If not so established in the
instrument evidencing the Option, the Option shall vest and

                                       6



become exercisable according to the following schedule, which may be waived or
modified by the Plan Administrator at any time:



   Period of Optionee's Continuous Employment               Portion of Total Option
   or Service With the Company or Its Related           That Is Vested and Exercisable
    Corporations From the Option Grant Date
                                                      
                  After one year                                      20%
                  After two years                                     40%
                  After three years                                   60%
                  After four years                                    80%
                  After five years                                   100%


     Notwithstanding the foregoing, an Option granted under Article I of the
Plan shall become 100% vested and exercisable on the date of termination of an
Optionee's employment or service relationship with the Company or a Related
Corporation on account of the Optionee's death, provided that the Optionee has
been in the continuous employment of or service to the Company or a Related
Corporation for at least two years at the date of such Optionee's death.

     The Plan Administrator may adjust the vesting schedule of an Option held by
an Optionee who works less than "full-time" as that term is defined by the Plan
Administrator.

     To the extent that the right to purchase shares has accrued thereunder, an
Option may be exercised from time to time by delivery to the Company of a stock
option exercise agreement or notice, in a form and in accordance with procedures
established by the Plan Administrator, setting forth the number of shares with
respect to which the Option is being exercised, the restrictions imposed on the
shares purchased under such exercise agreement, if any, and such representations
and agreements as may be required by the Company, accompanied by payment in full
as described in Article I, Section 7.5. An Option may not be exercised as to
less than a reasonable number of shares at any one time, as determined by the
Plan Administrator.

     7.5  Payment of Exercise Price.

     The exercise price for shares purchased under an Option shall be paid in
full to the Company by delivery of consideration equal to the product of the
Option exercise price and the

                                       7



number of shares purchased. Such consideration must be paid in cash or by check
or, unless the Plan Administrator in its sole discretion determines otherwise,
either at the time the Option is granted or at any time before it is exercised,
in any combination of

     (a)  cash or check;

     (b)  tendering (either actually or, if and so long as the Common Stock is
registered under Section 12(b) or 12(g) of the Exchange Act, by attestation)
shares of Common Stock already owned by the Optionee for at least six months (or
any shorter period necessary to avoid a charge to the Company's earnings for
financial reporting purposes) having a Fair Market Value on the day prior to the
exercise date equal to the aggregate Option exercise price;

     (c)  if and so long as the Common Stock is registered under Section 12(b)
or 12(g) of the Exchange Act, delivery of an exercise notice, together with
irrevocable instructions, to a brokerage firm designated by the Company to
deliver promptly to the Company the aggregate amount of sale or loan proceeds to
pay the Option exercise price and any withholding tax obligations that may arise
in connection with the exercise and the Company to deliver the certificates for
such purchased shares directly to such brokerage firm, all in accordance with
the regulations of the Federal Reserve Board; or

     (d)  such other consideration as the Plan Administrator may permit.

     In addition, to assist an Optionee (including an Optionee who is an officer
or a director of the Company) in acquiring shares of Common Stock pursuant to an
Option granted under the Plan, the Plan Administrator, in its sole discretion,
may authorize, either at the Grant Date or at any time before the acquisition of
Common Stock pursuant to the Option, (i) the payment by the Optionee of a
full-recourse promissory note, (ii) the payment by the Optionee of the purchase
price, if any, of the Common Stock in installments, or (iii) the guarantee by
the Company of a loan obtained by the Optionee from a third party. Subject to
the foregoing, the Plan Administrator shall in its sole discretion specify the
terms of any loans, installment payments or loan guarantees, including the
interest rate and terms of and security for repayment.

     7.6  Post-Termination Exercises.

     The Plan Administrator shall establish and set forth in each instrument
that evidences an Option whether the Option shall continue to be exercisable,
and the terms and conditions of

                                       8



such exercise, if an Optionee ceases to be employed by, or to provide services
to, the Company or its Related Corporations, which provisions may be waived or
modified by the Plan Administrator at any time. If not so established in the
instrument evidencing the Option, the Option shall be exercisable according to
the following terms and conditions, which may be waived or modified by the Plan
Administrator at any time:

     (a)  Any portion of an Option that is not vested and exercisable on the
date of termination of the Optionee's employment or service relationship (the
"Termination Date") shall expire on such date, unless the Plan Administrator
determines otherwise.

     (b)  Any portion of an Option that is vested and exercisable on the
Termination Date shall expire upon the earliest to occur of:

          (i)    the last day of the Option Term;

          (ii)   if the Optionee's Termination Date occurs for reasons other
than Cause, Disability, death or Retirement, the three-month anniversary of such
Termination Date; and

          (iii)  if the Optionee's Termination Date occurs by reason of
Disability, death or Retirement, the one-year anniversary of such Termination
Date.

     Notwithstanding the foregoing, if the Optionee dies after the Termination
Date while the Option is otherwise exercisable, the Option shall expire upon the
earlier to occur of (y) the last day of the Option Term and (z) the first
anniversary of the date of death.

     Also notwithstanding the foregoing, in case of termination of the
Optionee's employment or service relationship for Cause, the Option shall
automatically expire upon first notification to the Optionee of such
termination, unless the Plan Administrator determines otherwise. If an
Optionee's employment or service relationship with the Company is suspended
pending an investigation of whether the Optionee shall be terminated for Cause,
all the Optionee's rights under any Option likewise shall be suspended during
the period of investigation.

     An Optionee's transfer of employment or service relationship between or
among the Company and its Related Corporations, or a change in status from an
employee to a consultant that is evidenced by a written agreement between an
Optionee and the Company or a Related

                                       9



Corporation, shall not be considered a termination of employment or service
relationship for purposes of this Article I, Section 7. Employment or service
relationship shall be deemed to continue while the Optionee is on a bona fide
leave of absence, if such leave was approved by the Company or a Related
Corporation in writing and if continued crediting of service for purposes of
this Article I, Section 7 is expressly required by the terms of such leave or by
applicable law (as determined by the Company). The effect of a Company-approved
leave of absence on the terms and conditions of an Option shall be determined by
the Plan Administrator, in its sole discretion.

SECTION 8.  INCENTIVE STOCK OPTION LIMITATIONS.

     To the extent required by Section 422 of the Code, Incentive Stock Options
shall be subject to the following additional terms and conditions:

     8.1  Dollar Limitation.

     To the extent the aggregate Fair Market Value (determined as of the Grant
Date) of Common Stock with respect to which Incentive Stock Options are
exercisable for the first time during any calendar year (under the Plan and all
other stock option plans of the Company) exceeds $100,000, such portion in
excess of $100,000 shall be treated as a Nonqualified Stock Option. In the event
the Optionee holds two or more such Options that become exercisable for the
first time in the same calendar year, such limitation shall be applied on the
basis of the order in which such Options are granted.

     8.2  More Than 10% Stockholders.

     If an individual owns more than 10% of the total voting power of all
classes of the Company's stock, then the exercise price per share of an
Incentive Stock Option shall not be less than 110% of the Fair Market Value of
the Common Stock on the Grant Date and the Option Term shall not exceed five
years. The determination of more than 10% ownership shall be made in accordance
with Section 422 of the Code.

     8.3  Eligible Employees.

     Individuals who are not employees of the Company or one of its parent
corporations or subsidiary corporations may not be granted Incentive Stock
Options. For purposes of this

                                       10



Article I, Section 8.3, "parent corporation" and "subsidiary corporation" shall
have the meanings attributed to those terms for purposes of Section 422 of the
Code.

     8.4  Term.

     Except as provided in Article I, Section 8.2, the Option Term shall not
exceed 10 years.

     8.5  Exercisability.

     An Option designated as an Incentive Stock Option shall cease to qualify
for favorable tax treatment as an Incentive Stock Option to the extent it is
exercised (if permitted by the terms of the Option) (a) more than three months
after the Termination Date for reasons other than death or Disability, (b) more
than one year after the Termination Date by reason of Disability, or (c) after
the Optionee has been on leave of absence for more than 90 days, unless the
Optionee's reemployment rights are guaranteed by statute or contract.

     For purposes of this Article I, Section 8.5, Disability shall mean
"disability" as that term is defined for purposes of Section 422 of the Code.

     8.6  Taxation of Incentive Stock Options.

     In order to obtain certain tax benefits afforded to Incentive Stock Options
under Section 422 of the Code, the Optionee must hold the shares issued upon the
exercise of an Incentive Stock Option for two years after the Grant Date and one
year from the date of exercise. An Optionee may be subject to the alternative
minimum tax at the time of exercise of an Incentive Stock Option. The Optionee
shall give the Company prompt notice of any disposition of shares acquired by
the exercise of an Incentive Stock Option prior to the expiration of such
holding periods.

     8.7  Promissory Notes.

     The amount of any promissory note delivered pursuant to Article I, Section
7.5 in connection with an Incentive Stock Option shall bear interest at a rate
specified by the Plan Administrator, but in no case less than the rate required
to avoid imputation of interest (taking into account any exceptions to the
imputed interest rules) for federal income tax purposes.

                                       11



SECTION 9.   WITHHOLDING.

     The Company may require the Optionee to pay to the Company the amount of
any withholding taxes that the Company is required to withhold with respect to
the grant, vesting or exercise of any Option. Subject to the Plan and applicable
law, the Plan Administrator may, in its sole discretion, permit the Optionee to
satisfy withholding obligations, in whole or in part, by paying cash, by
electing to have the Company withhold shares of Common Stock or by transferring
shares of Common Stock to the Company, in such amounts as are equivalent to the
Fair Market Value of the withholding obligation. The Company shall have the
right to withhold from any Option or any shares of Common Stock issuable
pursuant to an Option or from any cash amounts otherwise due or to become due
from the Company to the Optionee an amount equal to such taxes. The Company may
also deduct from any Option any other amounts due from the Optionee to the
Company or a Related Corporation.

SECTION 10.  ASSIGNABILITY.

     Options granted under Article I of the Plan and any interest therein may
not be assigned, pledged or transferred by the Optionee and may not be made
subject to attachment or similar proceedings otherwise than by will or by the
applicable laws of descent and distribution, and, during the Optionee's
lifetime, such Options may be exercised only by the Optionee. Notwithstanding
the foregoing, and to the extent permitted by Section 422 of the Code, the Plan
Administrator, in its sole discretion, may permit such assignment, transfer and
exercisability and may permit an Optionee to designate a beneficiary who may
exercise the Option or receive compensation under the Option after the
Optionee's death; provided, however, that any Option so assigned or transferred
shall be subject to all the same terms and conditions contained in the
instrument evidencing the Option.

SECTION 11.  ADJUSTMENTS UPON CHANGES IN CAPITALIZATION.

     11.1  Adjustment of Shares.

     The aggregate number and class of shares for which Options may be granted
under the Plan, the number and class of shares covered by each outstanding
Option and the exercise price per share thereof (but not the total price), shall
all be proportionately adjusted for any increase or decrease in the number of
issued shares of Common Stock resulting from a split-up or consolidation of
shares or any like capital adjustment, or the payment of any stock dividend

                                       12



(not including the stock dividend approved by the Board of Directors of Immunex
on February 23, 1999).

     11.2  Cash, Stock or Other Property for Stock.

     Except as provided in Article I, Section 11.3, upon a merger (other than a
merger of the Company in which the holders of Common Stock immediately prior to
the merger have the same proportionate ownership of Common Stock in the
surviving corporation immediately after the merger), consolidation, acquisition
of property or stock, separation, reorganization (other than a mere
reincorporation or the creation of a holding company) or liquidation of the
Company, as a result of which the stockholders of the Company receive cash,
stock or other property in exchange for or in connection with their shares of
Common Stock, any Option granted hereunder shall terminate, but the Optionee
shall have the right immediately prior to any such merger, consolidation,
acquisition of property or stock, liquidation or reorganization to exercise such
Option in whole or in part whether or not the vesting requirements set forth in
the Option agreement have been satisfied.

     11.3  Conversion of Options on Stock for Stock Exchange.

     If the stockholders of the Company receive capital stock of another
corporation ("Exchange Stock") in exchange for their shares of Common Stock in
any transaction involving a merger (other than a merger of the Company in which
the holders of Common Stock immediately prior to the merger have the same
proportionate ownership of Common Stock in the surviving corporation immediately
after the merger), consolidation, acquisition of property or stock, liquidation
or reorganization (other than a mere reincorporation or the creation of a
holding company), the Company and the corporation issuing the Exchange Stock, in
their sole discretion, may determine that all Options granted hereunder shall be
converted into options to purchase shares of Exchange Stock instead of
terminating in accordance with the provisions of Article I, Section 11.2. The
amount and price of converted options shall be determined by adjusting the
amount and price of the Options granted hereunder in the same proportion as used
for determining the number of shares of Exchange Stock the holders of the Common
Stock receive in such merger, consolidation, acquisition of property or stock,
liquidation or reorganization. Unless accelerated by the Board, the vesting
schedule set forth in the Option agreement shall continue to apply to the
options granted for the Exchange Stock. The aggregate number and kind of shares
for which options may be granted under this Plan shall be

                                       13



proportionately adjusted in the event of such merger, consolidation, acquisition
of property or stock, liquidation or reorganization.

     11.4  Fractional Shares.

     In the event of any adjustment in the number of shares covered by any
Option, any fractional shares resulting from such adjustment shall be
disregarded and each such Option shall cover only the number of full shares
resulting from such adjustment.

     11.5  Determination of Board to Be Final.

     All Article I, Section 11 adjustments shall be made by the Plan
Administrator, and its determination as to what adjustments shall be made, and
the extent thereof, shall be final, binding and conclusive. Unless an Optionee
agrees otherwise, any change or adjustment to an Incentive Stock Option shall be
made in such a manner so as not to constitute a "modification" as defined in
Section 424(h) of the Code and so as not to cause his or her Incentive Stock
Option issued hereunder to fail to continue to qualify as an "incentive stock
option" as defined in Section 422(b) of the Code.

     11.6  Limitations.

     The grant of Options shall in no way affect the Company's right to adjust,
reclassify, reorganize or otherwise change its capital or business structure or
to merge, consolidate, dissolve, liquidate or sell or transfer all or any part
of its business or assets.

SECTION 12.  AMENDMENT AND TERMINATION OF PLAN.

     12.1  Amendment of Plan.

     The Plan may be amended only by the Board in such respects as it shall deem
advisable; provided, however, that to the extent required for compliance with
Section 422 of the Code or any applicable law or regulation, stockholder
approval shall be required for any amendment that would (a) increase the total
number of shares available for issuance under the Plan, (b) modify the class of
persons eligible to receive Options, or (c) otherwise require stockholder
approval under any applicable law or regulation. Any amendment made to the Plan
that would constitute a "modification" to Incentive Stock Options outstanding on
the date of such amendment shall

                                       14



not, without the consent of the Optionee, be applicable to such outstanding
Incentive Stock Options but shall have prospective effect only.

     12.2  Termination of Plan.

     The Board may suspend or terminate the Plan at any time. The Plan shall
have no fixed expiration date; provided, however, that no Incentive Stock
Options may be granted more than 10 years after the later of (a) the Plan's
adoption by the Board of Directors of Immunex and (b) the adoption by the Board
of Directors of Immunex of any amendment to the Plan that constitutes the
adoption of a new plan for purposes of Section 422 of the Code.

     12.3  Consent of Optionee.

     The amendment or termination of the Plan or the amendment of an outstanding
Option shall not, without the Optionee's consent, impair or diminish any rights
or obligations under any Option theretofore granted to the Optionee under the
Plan. Except as otherwise provided in the Plan, no outstanding Option shall be
terminated without the consent of the Optionee. Any change or adjustment to an
outstanding Incentive Stock Option shall not, without the consent of the
Optionee, be made in a manner so as to constitute a "modification" that would
cause such Incentive Stock Option to fail to continue to qualify as an Incentive
Stock Option.

SECTION 13.  GENERAL.

     13.1  Evidence of Options.

     Options granted under the Plan shall be evidenced by a written instrument
that shall contain such terms, conditions, limitations and restrictions as the
Plan Administrator shall deem advisable and that are not inconsistent with the
Plan.

     13.2  No Individual Rights.

     Nothing in the Plan or any Option granted under the Plan shall be deemed to
constitute an employment contract or confer or be deemed to confer on any
Optionee any right to continue in the employ of, or to continue any other
relationship with, the Company or any Related Corporation or limit in any way
the right of the Company or any Related Corporation of the

                                       15



Company to terminate an Optionee's employment or other relationship at any time,
with or without Cause.

     13.3  Registration.

     Notwithstanding any other provision of the Plan, the Company shall have no
obligation to issue or deliver any shares of Common Stock under the Plan or make
any other distribution of benefits under the Plan unless such issuance, delivery
or distribution would comply with all applicable laws (including, without
limitation, the requirements of the Securities Act), and the applicable
requirements of any securities exchange or similar entity.

     The Company shall be under no obligation to any Optionee to register for
offering or resale or to qualify for exemption under the Securities Act, or to
register or qualify under state securities laws, any shares of Common Stock,
security or interest in a security paid or issued under, or created by, the
Plan, or to continue in effect any such registrations or qualifications if made.
The Company may issue certificates for shares with such legends and subject to
such restrictions on transfer and stop-transfer instructions as counsel for the
Company deems necessary or desirable for compliance by the Company with federal
and state securities laws.

     To the extent that the Plan or any instrument evidencing an Option provides
for issuance of stock certificates to reflect the issuance of shares of Common
Stock, the issuance may be effected on a noncertificated basis, to the extent
not prohibited by applicable law or the applicable rules of any stock exchange.

     13.4  No Rights as a Stockholder.

     No Option shall entitle the Optionee to any cash dividend, voting or other
right of a stockholder unless and until the date of issuance under the Plan of
the shares that are the subject of such Option.

     13.5  Compliance With Laws and Regulations.

     Notwithstanding anything in the Plan to the contrary, the Plan
Administrator, in its sole discretion, may bifurcate the Plan so as to restrict,
limit or condition the use of any provision of the Plan to Optionees who are
officers or directors subject to Section 16 of the Exchange Act without so
restricting, limiting or conditioning the Plan with respect to other Optionees.

                                       16



Additionally, in interpreting and applying the provisions of the Plan, any
Option granted as an Incentive Stock Option pursuant to the Plan shall, to the
extent permitted by law, be construed as an "incentive stock option" within the
meaning of Section 422 of the Code.

     13.6  Optionees in Foreign Countries.

     The Plan Administrator shall have the authority to adopt such
modifications, procedures and subplans as may be necessary or desirable to
comply with provisions of the laws of foreign countries in which the Company or
its Related Corporations may operate to assure the viability of the benefits
from Options granted to Optionees employed in such countries and to meet the
objectives of the Plan.

     13.7  No Trust or Fund.

     The Plan is intended to constitute an "unfunded" plan. Nothing contained
herein shall require the Company to segregate any monies or other property, or
shares of Common Stock, or to create any trusts, or to make any special deposits
for any immediate or deferred amounts payable to any Optionee, and no Optionee
shall have any rights that are greater than those of a general unsecured
creditor of the Company.

     13.8   Severability.

     If any provision of the Plan or any Option is determined to be invalid,
illegal or unenforceable in any jurisdiction, or as to any person, or would
disqualify the Plan or any Option under any law deemed applicable by the Plan
Administrator, such provision shall be construed or deemed amended to conform to
applicable laws, or, if it cannot be so construed or deemed amended without, in
the Plan Administrator's determination, materially altering the intent of the
Plan or the Option, such provision shall be stricken as to such jurisdiction,
person or Option, and the remainder of the Plan and any such Option shall remain
in full force and effect.

     13.9   Choice of Law.

     The Plan and all determinations made and actions taken pursuant hereto, to
the extent not otherwise governed by the laws of the United States, shall be
governed by the laws of the State of Washington without giving effect to
principles of conflicts of laws.

                                       17



SECTION 14.  EFFECTIVE DATE.

     The Effective Date of the Original Plan was the date on which it was
adopted by the Board of Directors of Immunex, provided that it was approved by
Immunex's stockholders at any time within 12 months of such adoption.

SECTION 15.  ADDENDUM TO ARTICLE I OF THE PLAN.

     Notwithstanding anything in Article I of the Plan or any program adopted
under the Original Plan to the contrary, effective as of the Effective Time (as
defined in the Amended and Restated Agreement and Plan of Merger by and between
the Company, AMS Acquisition Inc. and Immunex dated as of December 16, 2001, as
amended by that certain First Amendment to Amended and Restated Agreement and
Plan of Merger dated as of July 15, 2002 (as amended, the "Merger Agreement")),
the following provisions shall constitute an addendum (the "Addendum") to
Article I of the Plan:

     15.1.  At the Effective Time, each option granted pursuant Article I of the
Plan shall be treated in accordance with the applicable terms of the Merger
Agreement.

     15.2.  In the event that an optionee's employment with Immunex or the
Company is terminated by the optionee for Good Reason or by Immunex or the
Company without Cause during the fifteen (15) months following the Effective
Time, each option held by such optionee for Common Stock that was granted
pursuant to the Merger Agreement with respect to (a) a Cancelled Company Option
(as defined in the Merger Agreement) or (b) an option for common stock of
Immunex that was granted after December 16, 2001, shall immediately vest in full
and shall remain exercisable until the earlier of (x) the first anniversary of
the optionee's termination of employment or (y) the end of the term of such
option.

     15.3.  In the event that an optionee who is a nonemployee director of
Immunex immediately prior to the Effective Time ceases to be a director of
Immunex or the Company for any reason immediately prior to, at, or during the
fifteen (15) months following the Effective Time, each option held by such
optionee for Common Stock shall immediately vest in full and shall remain
exercisable until the earlier of (x) the first anniversary of the date such
optionee ceases to be a director of Immunex or the Company or (y) the end of the
term of such option.

     15.4.  For purposes of this Addendum only, "Good Reason" shall mean the
occurrence on or after the Effective Time and without the optionee's consent of,
(a) a reduction in the

                                       18



optionee's annual base salary or wages, other than as part of a general
reduction applicable to substantially all employees of Immunex or the Company
employed in the United States or (ii) the relocation of the optionee's principal
place of employment to a location more than fifty (50) miles from the optionee's
principal place of employment prior to the Effective Time.

     15.5.  For purposes of this Addendum only, "Cause" shall mean (a) the
willful and continued failure by the optionee to substantially perform the
optionee's duties with Immunex or the Company (other than such failure resulting
form the optionee's incapacity due to physical or mental illness) or (b) the
willful engaging by the optionee in conduct which is demonstrably and materially
injurious to Immunex or the Company, monetarily or otherwise. For purposes of
this definition, no act, or failure to act, on the optionee's part shall be
deemed willful unless done, or omitted to be done, by the optionee not in good
faith or without reasonable belief that the optionee's act, or failure to act,
was in the best interest of Immunex or the Company.

                                   ARTICLE II.

                    PROVISIONS APPLICABLE TO OPTIONS GRANTED
                          ON OR AFTER RESTATEMENT DATE

     The following provisions of this Article II shall govern awards granted
under the Plan on or after the Restatement Date:

SECTION 1.  PURPOSE.

     (a)  The purpose of Article II of the Plan is to provide a means by which
employees or directors of and consultants to Amgen Inc., a Delaware corporation
(the "Company"), and its Affiliates, as defined in Article II, paragraph 1(b),
directly, or indirectly through Trusts, may be given an opportunity to benefit
from increases in value of the stock of the Company through the granting of (i)
incentive stock options, (ii) nonqualified stock options, (iii) stock bonuses,
and (iv) rights to purchase restricted stock, all as defined below.

     (b)  The word "Affiliate" as used in Article II of the Plan means any
parent corporation or subsidiary corporation of the Company, as those terms are
defined in Sections 424(e) and (f), respectively, of the Internal Revenue Code
of 1986, as amended (the "Code").

                                       19



     (c)  The Company, by means of Article II of the Plan, seeks to retain the
services of persons now employed by or serving as directors or consultants to
the Company, to secure and retain the services of persons capable of filling
such positions, and to provide incentives for such persons to exert maximum
efforts for the success of the Company.

     (d)  The Company intends that the rights issued under Article II of the
Plan ("Stock Awards") shall, in the discretion of the Board of Directors of the
Company (the "Board") or any committee to which responsibility for
administration of the Plan has been delegated pursuant to Article II, paragraph
2(c), be either (i) stock options granted pursuant to Article II, Sections 5 or
6 hereof, including incentive stock options as that term is used in Section 422
of the Code ("Incentive Stock Options"), or options which do not qualify as
Incentive Stock Options ("Nonqualified Stock Options") (together hereinafter
referred to as "Options"), or (ii) stock bonuses or rights to purchase
restricted stock granted pursuant to Article II, Section 7 hereof.

     (e)  The word "Trust" as used in Article II of the Plan shall mean a trust
created for the benefit of the employee, director or consultant, his or her
spouse, or members of their immediate family. The word optionee shall mean the
person to whom the option is granted or the employee, director or consultant for
whose benefit the option is granted to a Trust, as the context shall require.

SECTION 2.  ADMINISTRATION.

     (a)  The Plan shall be administered by the Board unless and until the Board
delegates administration to a committee, as provided in Article II, paragraph
2(c).

     (b)  The Board shall have the power, subject to, and within the limitations
of, the express provisions of the Plan:

          (1)  To determine from time to time which of the persons eligible
under the Plan shall be granted Stock Awards; when and how Stock Awards shall be
granted; whether a Stock Award will be an Incentive Stock Option, a Nonqualified
Stock Option, a stock bonus, a right to purchase restricted stock, or a
combination of the foregoing; the provisions of each Stock Award granted (which
need not be identical), including the time or times when a person shall be
permitted to purchase or receive stock pursuant to a Stock Award; and the number
of shares with respect to which Stock Awards shall be granted to each such
person.

                                       20



          (2)  To construe and interpret the Plan and Stock Awards granted under
it, and to establish, amend and revoke rules and regulations for its
administration. The Board, in the exercise of this power, may correct any
defect, omission or inconsistency in the Plan or in any Stock Award, in a manner
and to the extent it shall deem necessary or expedient to make the Plan fully
effective.

          (3)  To amend the Plan as provided in Article II, Section 14.

          (4)  Generally, to exercise such powers and to perform such acts as
the Board deems necessary or expedient to promote the best interests of the
Company.

     (c)  The Board may delegate administration of the Plan to a committee
composed of not fewer than two (2) members of the Board (the "Committee"). One
or more of these members may be non-employee directors and outside directors, if
required and as defined by the provisions of Article II, paragraphs 2(e) and
2(f). If administration is delegated to a Committee, the Committee shall have,
in connection with the administration of the Plan, the powers theretofore
possessed by the Board (except amendment of any program adopted pursuant to
Article II, Section 6 or any Non-Discretionary Director Awards granted
thereunder shall only be by action taken by the Board or a committee of one or
more members of the Board to which such authority has been specifically
delegated by the Board), subject, however, to such resolutions, not inconsistent
with the provisions of Article II of the Plan, as may be adopted from time to
time by the Board. Notwithstanding anything else in this Article II, paragraph
2(c) to the contrary, at any time the Board or the Committee may delegate to a
committee of one or more members of the Board the authority to grant or amend
options to all employees, directors or consultants or any portion or class
thereof.

     (d)  Notwithstanding anything else in the Plan to the contrary, at any time
the Board or the Committee may authorize by duly adopted resolution one or more
Officers (as defined below) (each a "Delegated Officer") to take the actions
described in Article II, paragraph 2(b)(1) of the Plan with respect to Options
only, subject to, and within the limitations of, the express provisions of
Article II of the Plan; provided, however, that a Delegated Officer shall not
have the power to (1) grant any Options to himself, any non-employee director,
consultant, Trust, other Delegated Officer or Officer, (2) determine the time or
times when a person shall be permitted to purchase stock pursuant to the
exercise of an Option (i.e., vesting), (3) determine the exercise price of an
Option, or (4) grant any Option to a parent corporation of the Company, as
defined in Section 424(e) of the Code. The resolution authorizing a Delegated

                                       21



Officer to act as such shall specify the total number of shares of Common Stock
that a Delegated Officer may grant with respect to Options. The exercise price
(including any formula by which such price or prices may be determined) and the
time or times when a person shall be permitted to purchase stock pursuant to the
exercise of an Option shall, however, be set by the Board or the Committee and
not by a Delegated Officer to the extent required by Delaware General
Corporation Law Section 157 or any other applicable law. The term "Officer"
shall include any natural person who is elected as a corporate officer of the
Company by the Board.

     (e)  The term "non-employee director" shall mean a member of the Board who
(i) is not currently an officer of the Company or a parent or subsidiary of the
Company (as defined in Rule 16a-1(f) promulgated by the Securities and Exchange
Commission under Section 16 of the Securities Exchange Act of 1934, as amended
(the "Exchange Act")) or an employee of the Company or a parent or subsidiary of
the Company; (ii) does not receive compensation from the Company or a parent or
subsidiary of the Company for services rendered in any capacity other than as a
member of the Board (including a consultant) in an amount required to be
disclosed to the Company's stockholders under Rule 404 of Regulation S-K
promulgated by the Securities and Exchange Commission ("Rule 404"); (iii) does
not possess an interest in any other transaction required to be disclosed under
Rule 404; or (iv) is not engaged in a business relationship required to be
disclosed under Rule 404, as all of these provisions are interpreted by the
Securities and Exchange Commission under Rule 16b-3 promulgated under the
Exchange Act.

     (f)  The term "outside director," as used in Article II of this Plan, shall
mean an administrator of the Plan, whether a member of the Board or of any
Committee to which responsibility for administration of the Plan has been
delegated pursuant to Article II, paragraph 2(c), who is considered to be an
"outside director" in accordance with the rules, regulations or interpretations
of Section 162(m) of the Code.

     (g)  Any requirement that an administrator of the Plan be a "non-employee
director" or "outside director" shall not apply if the Board or the Committee
expressly declares that such requirement shall not apply.

SECTION 3.  SHARES SUBJECT TO THE PLAN.

     (a)  Subject to the provisions of Article II, Section 11 relating to
adjustments upon

                                       22



changes in stock, the stock that may be issued pursuant to Stock Awards granted
under the Plan shall not exceed in the aggregate 19,267,763 shares of the
Company's $.0001 par value common stock (the "Common Stock"). If any Stock Award
granted under the Plan shall for any reason expire or otherwise terminate
without having been exercised in full, the Common Stock not purchased under such
Stock Award shall again become available for the Plan. Shares repurchased by the
Company pursuant to any repurchase rights reserved by the Company pursuant to
the Plan shall not be available for subsequent issuance under the Plan.

     (b)  The Common Stock subject to the Plan may be unissued shares or
reacquired shares, bought on the market or otherwise.

     (c)  An Incentive Stock Option may be granted to an eligible person under
the Plan only if the aggregate fair market value (determined at the time the
Incentive Stock Option is granted) of the Common Stock with respect to which
incentive stock options (as defined by the Code) are exercisable for the first
time by such optionee during any calendar year under all such plans of the
Company and its Affiliates does not exceed one hundred thousand dollars
($100,000). If it is determined that an entire Option or any portion thereof
does not qualify for treatment as an Incentive Stock Option by reason of
exceeding such maximum, such Option or the applicable portion shall be
considered a Nonqualified Stock Option.

SECTION 4.  ELIGIBILITY.

     (a)  Incentive Stock Options may be granted only to employees (including
officers) of the Company or its Affiliates. A director of the Company shall not
be eligible to receive Incentive Stock Options unless such director is also an
employee of the Company or any Affiliate. Stock Awards other than Incentive
Stock Options may be granted to employees (including officers) or directors of
or consultants to the Company or any Affiliate or to Trusts of any such
employee, director or consultant.

     (b)  A director shall in no event be eligible for the benefits of the Plan
(other than Non-Discretionary Director Awards, as defined in Article II, Section
6) unless and until such director is expressly declared eligible to participate
in the Plan by action of the Board or the Committee, and only if, at any time
discretion is exercised by the Board or the Committee in the selection of a
director as a person to whom Stock Awards may be granted, or in the
determination of the number of shares which may be covered by Stock Awards
granted to a director, the Plan complies with the requirements of Rule 16b-3
promulgated under the

                                       23



Exchange Act, as from time to time in effect. The Board shall otherwise comply
with the requirements of Rule 16b-3 promulgated under the Exchange Act, as from
time to time in effect. Notwithstanding the foregoing, the restrictions set
forth in this Article II, paragraph 4(b) shall not apply if the Board or
Committee expressly declares that such restrictions shall not apply.

     (c)  No person shall be eligible for the grant of an Incentive Stock Option
under the Plan if, at the time of grant, such person owns (or is deemed to own
pursuant to Section 424(d) of the Code) stock possessing more than ten percent
(10%) of the total combined voting power of all classes of stock of the Company
or of any of its Affiliates unless the exercise price of such Incentive Stock
Option is at least one hundred and ten percent (110%) of the fair market value
of the Common Stock at the date of grant and the Incentive Stock Option is not
exercisable after the expiration of five (5) years from the date of grant.

     (d)  Stock Awards shall be limited to a maximum of 649,155 shares of Common
Stock per person per calendar year.

SECTION 5.  TERMS OF DISCRETIONARY STOCK OPTIONS.

     An option granted pursuant to this Article II, Section 5 (a "Discretionary
Stock Option") shall be in such form and shall contain such terms and conditions
as the Board or the Committee shall deem appropriate. The provisions of separate
Options need not be identical, but each Option shall include (through
incorporation of provisions hereof by reference in the Option or otherwise) the
substance of each of the following provisions:

     (a)  No Option shall be exercisable after the expiration of ten (10) years
from the date it was granted.

     (b)  The exercise price of each Incentive Stock Option and each
Nonqualified Stock Option shall be not less than one hundred percent (100%) of
the fair market value of the Common Stock subject to the Option on the date the
Option is granted.

     (c)  The purchase price of Common Stock acquired pursuant to an Option
shall be paid, to the extent permitted by applicable statutes and regulations,
either: (i) in cash at the time the Option is exercised; or (ii) at the
discretion of the Board or the Committee, either at the time of grant or
exercise of the Option (A) by delivery to the Company of shares of Common Stock

                                       24



that have been held for the period required to avoid a charge to the Company's
reported earnings and valued at the fair market value on the date of exercise,
(B) according to a deferred payment or other arrangement with the person to whom
the Option is granted or to whom the Option is transferred pursuant to Article
II, paragraph 5(d), or (C) in any other form of legal consideration that may be
acceptable to the Board or the Committee in their discretion; including but not
limited to payment of the purchase price pursuant to a program developed under
Regulation T as promulgated by the Federal Reserve Board which results in the
receipt of cash (or a check) by the Company before Common Stock is issued or the
receipt of irrevocable instruction to pay the aggregate exercise price to the
Company from the sales proceeds before Common Stock is issued.

     In the case of any deferred payment arrangement, interest shall be payable
at least annually and shall be charged at not less than the minimum rate of
interest necessary to avoid the treatment as interest, under any applicable
provisions of the Code, of any amounts other than amounts stated to be interest
under the deferred payment arrangement.

     (d)  An Option granted to a natural person shall be exercisable during the
lifetime of such person only by such person, provided that such person during
such person's lifetime may designate a Trust to be such person's beneficiary
with respect to any Incentive Stock Options and with respect to any Nonqualified
Stock Options, and such beneficiary shall, after the death of the person to whom
the Option was granted, have all the rights that such person has while living,
including the right to exercise the Option. In the absence of such designation,
after the death of the person to whom the Option is granted, the Option shall be
exercisable by the person or persons to whom the optionee's rights under such
Option pass by will or by the laws of descent and distribution.

     (e)  The total number of shares of Common Stock subject to an Option may,
but need not, be allotted in periodic installments (which may, but need not, be
equal). From time to time during each of such installment periods, the Option
may become exercisable ("vest") with respect to some or all of the shares
allotted to that period, and may be exercised with respect to some or all of the
shares allotted to such period and/or any prior period as to which the Option
was not fully exercised. During the remainder of the term of the Option (if its
term extends beyond the end of the installment periods), the Option may be
exercised from time to time with respect to any shares then remaining subject to
the Option. The provisions of this Article II, paragraph 5(e) are subject to any
Option provisions governing the minimum number of shares as to which an Option
may be exercised.

                                       25



     (f)  The Company may require any optionee, or any person to whom an Option
is transferred under Article II, paragraph 5(d), as a condition of exercising
any such Option: (i) to give written assurances satisfactory to the Company as
to such person's knowledge and experience in financial and business matters
and/or to employ a purchaser representative who has such knowledge and
experience in financial and business matters, and that such person is capable of
evaluating, alone or together with the purchaser representative, the merits and
risks of exercising the Option; and (ii) to give written assurances satisfactory
to the Company stating that such person is acquiring the Common Stock subject to
the Option for such person's own account and not with any present intention of
selling or otherwise distributing the Common Stock. These requirements, and any
assurances given pursuant to such requirements, shall be inoperative if: (x) the
issuance of the shares upon the exercise of the Option has been registered under
a then currently effective registration statement under the Securities Act of
1933, as amended (the "Securities Act"); or (y) as to any particular
requirement, a determination is made by counsel for the Company that such
requirement need not be met in the circumstances under the then applicable
securities law.

     (g)  An Option shall terminate three (3) months after termination of the
optionee's employment or relationship as a consultant or director with the
Company or an Affiliate, unless: (i) such termination is due to the optionee's
permanent and total disability, within the meaning of Section 422(c)(6) of the
Code and with such permanent and total disability being certified by the Social
Security Administration prior to such termination, in which case the Option may,
but need not, provide that it may be exercised at any time within one (1) year
following such termination of employment or relationship as a consultant or
director; (ii) the optionee dies while in the employ of or while serving as a
consultant or director to the Company or an Affiliate, or within not more than
three (3) months after termination of such employment or relationship as a
consultant or director, in which case the Option may, but need not, provide that
it may be exercised at any time within eighteen (18) months following the death
of the optionee by the person or persons to whom the optionee's rights under
such Option pass by will or by the laws of descent and distribution; or (iii)
the Option by its term specifies either (A) that it shall terminate sooner than
three (3) months after termination of the optionee's employment or relationship
as a consultant or director with the Company or an Affiliate; or (B) that it may
be exercised more than three (3) months after termination of the optionee's
employment or relationship as a consultant or director with the Company or an
Affiliate. This Article II, paragraph 5(g) shall not be construed to extend the
term of any Option or to permit anyone to exercise the Option after expiration
of its term, nor shall it be construed to increase the number

                                       26



of shares as to which any Option is exercisable from the amount exercisable on
the date of termination of the optionee's employment or relationship as a
consultant or director.

     (h)  The Option may, but need not, include a provision whereby the optionee
may elect at any time during the term of the optionee's employment or
relationship as a consultant or director with the Company or any Affiliate to
exercise the Option as to any part or all of the shares subject to the Option
prior to the stated vesting dates of the Option. Any shares so purchased from
any unvested installment or Option may be subject to a repurchase right in favor
of the Company or to any other restriction the Board or the Committee determines
to be appropriate.

     (i)  To the extent provided by the terms of an Option, each optionee may
satisfy any federal, state or local tax withholding obligation relating to the
exercise of such Option by any of the following means or by a combination of
such means: (i) tendering a cash payment; (ii) authorizing the Company to
withhold from the shares of the Common Stock otherwise issuable to the optionee
as a result of the exercise of the Option a number of shares having a fair
market value less than or equal to the amount of the Company's required minimum
statutory withholding; or (iii) delivering to the Company owned and unencumbered
shares of the Common Stock having a fair market value less than or equal to the
amount of the Company's required minimum statutory withholding.

SECTION 6.  NON-DISCRETIONARY DIRECTOR AWARDS.

     The Board may from time to time adopt award programs under the Plan
providing for the grant of formula or non-discretionary Stock Awards to
directors of the Company who are not employees of the Company or any Affiliate
("Non-Discretionary Director Awards"). The terms and conditions of any such
program shall be established by the Board in its sole discretion, subject to the
terms and conditions of the Plan.

SECTION 7.  TERMS OF STOCK BONUSES AND PURCHASES OF RESTRICTED STOCK.

     Each stock bonus or restricted stock purchase agreement shall be in such
form and shall contain such terms and conditions as the Board or the Committee
shall deem appropriate. The terms and conditions of stock bonus or restricted
stock purchase agreements may change from time to time, and the terms and
conditions of separate agreements need not be identical, but

                                       27



each stock bonus or restricted stock purchase agreement shall include (through
incorporation of provisions hereof by reference in the agreement or otherwise)
the substance of each of the following provisions as appropriate:

     (a)  The purchase price under each stock purchase agreement shall be such
amount as the Board or Committee shall determine and designate in such
agreement. Notwithstanding the foregoing, the Board or the Committee may
determine that eligible participants in the Plan may be awarded stock pursuant
to a stock bonus agreement in consideration for past services actually rendered
to the Company or for its benefit.

     (b)  No rights under a stock bonus or restricted stock purchase agreement
shall be assignable by any participant under the Plan, either voluntarily or by
operation of law, except where such assignment is required by law or expressly
authorized by the terms of the applicable stock bonus or restricted stock
purchase agreement.

     (c)  The purchase price of stock acquired pursuant to a stock purchase
agreement shall be paid either: (i) in cash at the time of purchase; (ii) at the
discretion of the Board or the Committee, according to a deferred payment or
other arrangement with the person to whom the Common Stock is sold; or (iii) in
any other form of legal consideration that may be acceptable to the Board or the
Committee in their discretion; including but not limited to payment of the
purchase price pursuant to a program developed under Regulation T as promulgated
by the Federal Reserve Board which results in the receipt of cash (or a check)
by the Company before Common Stock is issued or the receipt of irrevocable
instruction to pay the aggregate exercise price of the Company from the sales
proceeds before Common Stock is issued. Notwithstanding the foregoing, the Board
or the Committee to which administration of the Plan has been delegated may
award Common Stock pursuant to a stock bonus agreement in consideration for past
services actually rendered to the Company or for its benefit.

     (d)  Shares of Common Stock sold or awarded under the Plan may, but need
not, be subject to a repurchase option in favor of the Company in accordance
with a vesting schedule to be determined by the Board or the Committee.

     (e)  In the event a person ceases to be an employee of or ceases to serve
as a director or consultant to the Company or an Affiliate, the Company may
repurchase or otherwise reacquire any or all of the shares of Common Stock held
by that person which have not vested as of the date of termination under the
terms of the stock bonus or restricted stock purchase

                                       28



agreement between the Company and such person.

     (f)  To the extent provided by the terms of a stock bonus or restricted
stock purchase agreement, a participant may satisfy any federal, state or local
tax withholding obligation relating to the lapsing of a repurchase option in
favor of the Company or vesting of a stock bonus or a restricted stock award by
any of the following means or by a combination of such means: (i) tendering a
cash payment; (ii) authorizing the Company to withhold from the shares of the
Common Stock otherwise deliverable to a participant as a result of the lapsing
of a repurchase option in favor of the Company or the vesting of a stock bonus
or a restricted stock award a number of shares having a fair market value less
than or equal to the amount of the Company's required minimum statutory
withholding; or (iii) delivering to the Company owned and unencumbered shares of
the Common Stock having a fair market value less than or equal to the amount of
the Company's required minimum statutory withholding.

SECTION 8.  COVENANTS OF THE COMPANY.

     (a)  During the terms of the Stock Awards granted under the Plan, the
Company shall keep available at all times the number of shares of Common Stock
required to satisfy such Stock Awards up to the number of shares of Common Stock
authorized under the Plan.

     (b)  The Company shall seek to obtain from each regulatory commission or
agency having jurisdiction over the Plan such authority as may be required to
issue and sell shares of Common Stock under the Stock Awards granted under the
Plan; provided, however, that this undertaking shall not require the Company to
register under the Securities Act either the Plan, any Stock Award granted under
the Plan or any Common Stock issued or issuable pursuant to any such Stock
Award. If, after reasonable efforts, the Company is unable to obtain from any
such regulatory commission or agency the authority that counsel for the Company
deems necessary for the lawful issuance and sale of Common Stock under the Plan,
the Company shall be relieved from any liability for failure to issue and sell
Common Stock upon exercise of such Stock Awards unless and until such authority
is obtained.

SECTION 9.  USE OF PROCEEDS FROM COMMON STOCK.

     Proceeds from the sale of Common Stock pursuant to Stock Awards granted
under the Plan shall constitute general funds of the Company.

                                       29



SECTION 10.  MISCELLANEOUS.

     (a)  The Board or Committee shall have the power to accelerate the time
during which a Stock Award may be exercised or the time during which a Stock
Award or any part thereof will vest, notwithstanding the provisions in the Stock
Award stating the time during which it may be exercised or the time during which
it will vest. Each Discretionary Stock Option providing for vesting pursuant to
Article II, paragraph 5(e) shall also provide that if the employee's employment
or a director's or consultant's affiliation with the Company or an Affiliate of
the Company is terminated by reason of death or disability (within the meaning
of Title II or XVI of the Social Security Act or comparable statute applicable
to an Affiliate and with such permanent and total disability certified by (i)
the Social Security Administration, (ii) the comparable governmental authority
applicable to an Affiliate, (iii) such other body having the relevant
decision-making power applicable to an Affiliate or (iv) an independent medical
advisor appointed by the Company, as applicable, prior to such termination),
then the vesting schedule of Discretionary Stock Options granted to such
employee, director or consultant or to the Trusts of such employee, director or
consultant shall be accelerated by twelve months for each full year the employee
has been employed by or the director or consultant has been affiliated with the
Company and/or an Affiliate of the Company.

     (b)  Neither an optionee nor any person to whom an Option is transferred
under the provisions of the Plan shall be deemed to be the holder of, or to have
any of the rights of a holder with respect to, any shares subject to such Option
unless and until such person has satisfied all requirements for exercise of the
Option pursuant to its terms.

     (c)  Nothing in the Plan or any instrument executed or Stock Award granted
pursuant thereto shall confer upon any eligible employee, consultant, director,
optionee or holder of Stock Awards under the Plan any right to continue in the
employ of the Company or any Affiliate or to continue acting as a consultant or
director or shall affect the right of the Company or any Affiliate to terminate
the employment or consulting relationship or directorship of any eligible
employee, consultant, director, optionee or holder of Stock Awards under the
Plan with or without cause. In the event that a holder of Stock Awards under the
Plan is permitted or otherwise entitled to take a leave of absence, the Company
shall have the unilateral right to (i) determine whether such leave of absence
will be treated as a termination of employment or relationship as consultant or
director for purposes hereof, and (ii) suspend or otherwise delay the time or
times at which exercisability or vesting would otherwise occur with respect to
any outstanding Stock Awards under the Plan.

                                       30



SECTION 11.  ADJUSTMENTS UPON CHANGES IN COMMON STOCK.

     If any change is made in the Common Stock subject to the Plan, or subject
to any Stock Award granted under the Plan (through merger, consolidation,
reorganization, recapitalization, stock dividend, dividend in property other
than cash, stock split, liquidating dividend, combination of shares, exchange of
shares, change in corporate structure or other transaction not involving the
receipt of consideration by the Company), the Plan and outstanding Stock Awards
will be appropriately adjusted in the class(es) and maximum number of shares
subject to the Plan, the maximum number of shares which may be granted to a
participant in a calendar year, the class(es) and number of shares and price per
share of stock subject to outstanding Stock Awards, and the number of shares of
Common Stock to be granted as Non-Discretionary Director Awards, if any. Such
adjustment shall be made by the Board or the Committee, the determination of
which shall be final, binding and conclusive. (The conversion of any convertible
securities of the Company shall not be treated as a "transaction not involving
the receipt of consideration".)

SECTION 12.  CHANGE OF CONTROL.

     (a)  Notwithstanding anything to the contrary in this Plan, in the event of
a Change in Control (as hereinafter defined), then, to the extent permitted by
applicable law: (i) the time during which Stock Awards become vested shall
automatically be accelerated so that the unvested portions of all Stock Awards
shall be vested prior to the Change in Control and (ii) the time during which
the Options may be exercised shall automatically be accelerated to prior to the
Change in Control. Upon and following the acceleration of the vesting and
exercise periods, at the election of the holder of the Stock Award, the Stock
Award may be: (x) exercised (with respect to Options) or, if the surviving or
acquiring corporation agrees to assume the Stock Awards or substitute similar
stock awards, (y) assumed; or (z) replaced with substitute stock awards. Options
not exercised, substituted or assumed prior to or upon the Change in Control
shall be terminated.

     (b)  For purposes of Article II of the Plan, a "Change of Control" shall be
deemed to have occurred at any of the following times:

          (i)  upon the acquisition (other than from the Company) by any person,
entity or "group," within the meaning of Section 13(d)(3) or 14(d)(2) of the
Exchange Act (excluding,

                                       31



for this purpose, the Company or its affiliates, or any employee benefit plan of
the Company or its affiliates which acquires beneficial ownership of voting
securities of the Company), of beneficial ownership (within the meaning of Rule
13d-3 promulgated under the Exchange Act) of fifty percent (50%) or more of
either the then outstanding shares of Common Stock or the combined voting power
of the Company's then outstanding voting securities entitled to vote generally
in the election of directors; or

          (ii)   at the time individuals who, as of July 15, 2002, constitute
the Board (the "Incumbent Board") cease for any reason to constitute at least a
majority of the Board, provided that any person becoming a director subsequent
to July 15, 2002, whose election, or nomination for election by the Company's
stockholders, was approved by a vote of at least a majority of the directors
then comprising the Incumbent Board (other than an election or nomination of an
individual whose initial assumption of office is in connection with an actual or
threatened election contest relating to the election of the Directors of the
Company, as such terms are used in Rule 14a-11 of Regulation 14A promulgated
under the Exchange Act) shall be, for purposes of Article II of the Plan,
considered as though such person were a member of the Incumbent Board; or

          (iii)  immediately prior to the consummation by the Company of a
reorganization, merger, consolidation, (in each case, with respect to which
persons who were the stockholders of the Company immediately prior to such
reorganization, merger or consolidation do not, immediately thereafter, own more
than fifty percent (50%) of the combined voting power entitled to vote generally
in the election of directors of the reorganized, merged or consolidated
company's then outstanding voting securities) or a liquidation or dissolution of
the Company or of the sale of all or substantially all of the assets of the
Company; or

          (iv)   the occurrence of any other event which the Incumbent Board in
its sole discretion determines constitutes a Change of Control.

SECTION 13.  QUALIFIED DOMESTIC RELATIONS ORDERS

     (a)  Anything in the Plan to the contrary notwithstanding, rights under
Stock Awards may be assigned to an Alternate Payee to the extent that a QDRO so
provides. (The terms "Alternate Payee" and "QDRO" are defined in Article II,
paragraph 13(c) below.) The assignment of a Stock Award to an Alternate Payee
pursuant to a QDRO shall not be treated as

                                       32



having caused a new grant. The transfer of an Incentive Stock Option to an
Alternate Payee may, however, cause it to fail to qualify as an Incentive Stock
Option. If a Stock Award is assigned to an Alternate Payee, the Alternate Payee
generally has the same rights as the grantee under the terms of the Plan;
provided however, that (i) the Stock Award shall be subject to the same vesting
terms and exercise period as if the Stock Award were still held by the grantee
and (ii) an Alternate Payee may not transfer a Stock Award.

     (b)  In the event of the Plan administrator's receipt of a domestic
relations order or other notice of adverse claim by an Alternate Payee of a
grantee of a Stock Award, transfer of the proceeds of the exercise of such Stock
Award, whether in the form of cash, stock or other property, may be suspended.
Such proceeds shall thereafter be transferred pursuant to the terms of a QDRO or
other agreement between the grantee and Alternate Payee. A grantee's ability to
exercise a Stock Award may be barred if the Plan administrator receives a court
order directing the Plan administrator not to permit exercise.

     (c)  The word "QDRO" as used in Article II of the Plan shall mean a court
order (i) that creates or recognizes the right of the spouse, former spouse or
child (an "Alternate Payee") of an individual who is granted a Stock Award to an
interest in such Stock Award relating to marital property rights or support
obligations and (ii) that the administrator of the Plan determines would be a
"qualified domestic relations order," as that term is defined in section 414(p)
of the Code and section 206(d) of the Employee Retirement Income Security Act
("ERISA"), but for the fact that the Plan is not a plan described in section
3(3) of ERISA.

SECTION 14.  AMENDMENT OF THE PLAN.

     (a)  The Board at any time, and from time to time, may amend the Plan.
However, except as provided in Article II, Section 11 relating to adjustments
upon changes in the Common Stock, no amendment shall be effective unless
approved by the stockholders of the Company within twelve (12) months before or
after the adoption of the amendment, where the amendment will:

          (i)  increase the number of shares reserved for Stock Awards under the
Plan;

          (ii) modify the requirements as to eligibility for participation in
the Plan (to the extent such modification requires stockholder approval in order
for the Plan to satisfy the requirements of Section 422(b) of the Code); or

                                       33



          (iii)  modify the Plan in any other way if such modification requires
stockholder approval in order for the Plan to satisfy the requirements of
Section 422(b) of the Code.

     (b)  The Board may in its sole discretion submit any other amendment to the
Plan for stockholder approval, including, but not limited to, amendments to the
Plan intended to satisfy the requirements of Section 162(m) of the Code and the
regulations promulgated thereunder regarding the exclusion of performance-based
compensation from the limit on corporate deductibility of compensation to
certain executive officers.

     (c)  It is expressly contemplated that the Board may amend the Plan in any
respect the Board deems necessary or advisable to provide optionees with the
maximum benefits provided or to be provided under the provisions of the Code and
the regulations promulgated thereunder relating to employee Incentive Stock
Options and/or to bring the Plan and/or Options granted under it into compliance
therewith.

     (d)  Rights and obligations under any Stock Award granted before amendment
of the Plan shall not be impaired by any amendment of the Plan, unless: (i) the
Company requests the consent of the person to whom the Stock Award was granted;
and (ii) such person consents in writing.

SECTION 15.  TERMINATION OR SUSPENSION OF THE PLAN.

     (a)  The Board may suspend or terminate the Plan at any time. No Stock
Awards may be granted under the Plan while the Plan is suspended or after it is
terminated. No Incentive Stock Options may be granted under the Plan after
February 22, 2009.

     (b)  Rights and obligations under any Stock Awards granted while the Plan
is in effect shall not be impaired by suspension or termination of the Plan,
except with the consent of the person to whom the Stock Award was granted.

                                       34




                           STOCK OPTION GRANT PROGRAM
                                       FOR
                         NONEMPLOYEE DIRECTORS UNDER THE
                               IMMUNEX CORPORATION
                   AMENDED AND RESTATED 1999 STOCK OPTION PLAN

     The following provisions set forth the terms of the stock option grant
program (the "Program") for nonemployee directors of Immunex Corporation (the
"Company") under the Company's Amended and Restated 1999 Stock Option Plan (the
"Plan"). The following terms are intended to supplement, not alter or change,
the provisions of the Plan, and in the event of any inconsistency between the
terms contained herein and in the Plan, the Plan shall govern. All capitalized
terms that are not defined herein shall be as defined in the Plan.

     1. Administration

     The Board shall be the Plan Administrator of the Program. Subject to the
terms of the Program, the Plan Administrator shall have the power to construe
the provisions of the Program, to determine all questions arising hereunder and
to adopt and amend such rules and regulations for the administration of the
Program as it may deem desirable.

     2. Eligibility

     Each member of the Board elected or appointed who is not otherwise an
employee of the Company, any Parent or Subsidiary, or a director appointed by
American Cyanamid Company or American Home Products Corporation pursuant to the
Amended and Restated Governance Agreement among American Cyanamid Company,
Lederle Oncology Corporation and Immunex Corporation dated as of December 15,
1992 (an "Eligible Director") shall be eligible to receive Initial Grants and
Annual Grants under the Program.

     3. Initial Grants

     Subject to Sections 9 and 12 hereof, each Eligible Director who is elected
or appointed for the first time after the date of adoption of the Program shall
automatically receive the grant of an Option to purchase 30,000 shares on the
day such Eligible Director is initially elected or appointed (an "Initial
Grant").

     4. Annual Grants

     Subject to Sections 9 and 12 hereof, each Eligible Director continuing
service as an Eligible Director immediately following an annual meeting of
shareholders shall automatically receive an Option to purchase 20,000 shares
immediately following each year's annual meeting of shareholders as an annual
grant (an "Annual Grant"); provided, however, that an Eligible



Director who received an Initial Grant on such date shall not receive an Annual
Grant until the next annual meeting.

     5. Option Exercise Price

     The exercise price of an Option shall be the Fair Market Value of the
Common Stock on the effective date of an Initial or Annual Grant.

     6. Vesting and Exercisability

     Each Option granted to an Eligible Director shall vest and become
exercisable in accordance with the following vesting schedule:

  Period of Eligible Director's Continuous
Service as a Director With the Company From     Portion of Total Option Which Is
              the Grant Date                         Vested and Exercisable
- -------------------------------------------     --------------------------------
              Less than twelve months                           0%

                   Twelve months                               20%

                 Twenty-four months                            40%

                 Thirty-six months                             60%

                 Forty-eight months                            80%

               Sixty months or greater                        100%

     Notwithstanding the foregoing, an Option granted under the Program shall
become 100% vested and exercisable on the date of termination of an Eligible
Director's service as a member of the Board on account of the Eligible
Director's death, provided that the Eligible Director has served as a member of
the Board for at least two years at the date of such Eligible Director's death.

     7. Manner of Option Exercise

     An Option shall be exercised by giving the required notice to the Company,
stating the number of shares of Common Stock with respect to which the Option is
being exercised, accompanied by payment in full for such Common Stock, which
payment may be in any combination of (a) cash or check, (b) tendering (either
actually or, if and so long as the Common Stock is registered under Section
12(b) or 12(g) of the Exchange Act, by attestation) shares of Common Stock
already owned by the Eligible Director for at least six months (or any minimum
period necessary to avoid a charge to the Company's earnings for financial
reporting purposes) having a Fair Market Value on the day prior to the exercise
date equal to the aggregate Option exercise price; or (c) if and so long as the
Common Stock is registered under the Exchange Act, by delivery of a properly
executed exercise notice, together with irrevocable instructions to a broker, to
promptly deliver to the Company the amount of sale or loan proceeds to pay the

                                      -2-



Option exercise price and the Company to deliver the certificates for such
purchased shares directly to such broker, all in accordance with the regulations
of the Federal Reserve Board.

     8. Term of Options

     Each Option shall expire ten years from the Grant Date thereof, but shall
be subject to earlier termination as follows:

     (a) In the event that an Eligible Director ceases to be a director of the
Company for any reason other than the death of the Eligible Director, the
unvested portion of any Option granted to such Eligible Director shall terminate
immediately and the vested portion of the Option may be exercised by the
Eligible Director only within three months after the date he or she ceases to be
a director of the Company or prior to the date on which the Option expires by
its terms, whichever is earlier.

     (b) In the event of the termination of an Eligible Director's service as a
member of the Board on account of the Eligible Director's death, the vested
portion of any Option granted to such Eligible Director may be exercised within
one year after the date of death of the Eligible Director or prior to the date
on which the Option expires by its terms, whichever is earlier, by the personal
representative of the Eligible Director's estate, the person(s) to whom the
Eligible Director's rights under the Option have passed by will or the
applicable laws of descent and distribution or the beneficiary designated
pursuant to the Plan.

     (c) In the event of the death of an Eligible Director subsequent to the
termination of an Eligible Director's services, but prior to the expiration of
the three-month exercise period referred to in Section 8(a) above, the vested
portion of the Option at the time of the termination of the Eligible Directors
services may be exercised within one year after the date of the termination of
the Eligible Director's services or prior to the date on which the Option
expires by its terms, whichever is earlier, by the personal representative of
the Eligible Director's estate, the person(s) to whom the Eligible Director's
rights under the Option have passed by will or the applicable laws of descent
and distribution or the beneficiary designated pursuant to the Plan.

     9. Adjustments

     The number and class of shares covered by each outstanding Option and the
exercise price per share thereof (but not the total price) shall all be
proportionately adjusted for any stock dividends, stock splits,
recapitalizations, combinations or exchanges of shares, split-ups, split-offs,
spinoffs, or other similar changes in capitalization. Notwithstanding the
foregoing, if an automatic grant occurs within ninety days following any such
change in capitalization, the aggregate number and class of shares subject to
such automatic grant shall be proportionately adjusted to be the same number and
class of shares that would be subject to the automatic grant had it been
outstanding immediately prior to the date of such change in capitalization. Upon
the effective date of a dissolution or liquidation of the Company, or of a
reorganization, merger or consolidation of the Company with one or more
corporations that results in more than 70% of the outstanding voting shares of
the Company being owned by one or more affiliated corporations or other
affiliated entities, or of a transfer of all or substantially all the assets or
more than 70% of the then outstanding shares of the Company to another
corporation or other entity, the Program

                                      -3-



and all Options granted hereunder shall terminate. In the event of such
dissolution, liquidation, reorganization, merger, consolidation, transfer of
assets or transfer of stock, each Eligible Director shall be entitled, for a
period of twenty days prior to the effective date of such transaction, to
purchase the full number of shares under his or her Option which he or she
otherwise would have been entitled to purchase during the remaining term of such
Option.

     Adjustments under this Section 9 shall be made by the Plan Administrator,
whose determination shall be final. In the event of any adjustment in the number
of shares covered by any Option, any fractional shares resulting from such
adjustment shall be disregarded and each such Option shall cover only the number
of full shares resulting from such adjustment.

     10. Compliance with Rule 16b-3

     It is the intention of the Company that the Program comply in all respects
with the requirements for a "formula plan" within the meaning attributed to that
term for purposes of Rule 16b-3 promulgated under Section 16(b) of the Exchange
Act. Therefore, if any provision is later found not to be in compliance with
such requirements, that provision shall be deemed null and void, and in all
events the Program shall be construed in favor of its meeeting such
requirements.

     11. Amendment, Suspension or Termination

     The Board may amend the provisions contained in the Program in such
respects as it deems advisable. The Board may also suspend or terminate the
Program. Any such amendment, suspension or termination shall not, without the
consent of the Eligible Director, impair or diminish any rights of an Eligible
Director under an Option.

     Provisions of the Plan (including any amendments) that were not discussed
above, to the extent applicable to Eligible Directors, shall continue to govern
the terms and conditions of Options granted to Eligible Directors.

     12. Effective Date

     The Program shall become effective on the day the Board approves the
adoption of the Program.

     Adopted by the Board on February 8, 2001.

                                      -4-

                                                                    Exhibit 10.3

                         AMGEN INC. AMENDED AND RESTATED
                        1999 EMPLOYEE STOCK PURCHASE PLAN

SECTION 1.   PURPOSE

     The purposes of the Amgen Inc. Amended and Restated 1999 Employee Stock
Purchase Plan (the "Plan") are (a) to assist employees of Immunex Corporation, a
Washington corporation ("Immunex"), and its designated subsidiaries in acquiring
a stock ownership interest in Amgen Inc., a Delaware corporation and parent
corporation of Immunex (the "Company"), pursuant to a plan that is intended to
qualify as an "employee stock purchase plan" under Section 423 of the Internal
Revenue Code of 1986, as amended, and (b) to encourage employees to remain in
the employ of Immunex and its subsidiaries. This Plan amends and restates in its
entirety the Immunex Corporation 1999 Employee Stock Purchase Plan, as amended
and restated.

SECTION 2.   DEFINITIONS

     For purposes of the Plan, the following terms shall be defined as set forth
below.

     "Board" means the Board of Directors of the Company.

     "Code" means the Internal Revenue Code of 1986, as amended.

     "Committee" means the Compensation Committee of the Board.

     "Common Stock" means the common stock, par value $0.0001 per share, of the
Company.

     "Company" has the meaning set forth in Section 1.

     "Designated Subsidiary" has the meaning set forth under the definition of
"Eligible Employee" in this Section 2.

     "Eligible Compensation" means all salary and wages including overtime.
Regular cash compensation does not include cash bonuses, commissions, severance
pay, hiring and relocation bonuses, pay in lieu of vacations, sick leave, gain
from stock option exercises or any other special payments.

     "Eligible Employee" means any employee of Immunex or any domestic
Subsidiary Corporation or any other Subsidiary Corporation designated by the
Board or the Committee (each a "Designated Subsidiary"), who is in the employ of
Immunex (or any Designated Subsidiary) on one or more Offering Dates and who
meets the following criteria:

             (a) the employee does not, immediately after the option is granted,
own stock (as defined by the Code) possessing 5% or more of the total combined
voting power or value of all classes of stock of Immunex or of a Parent
Corporation or Subsidiary Corporation of Immunex;

             (b) the employee's customary employment is for 20 hours or more per
week; provided, however, that the Plan Administrator may increase or decrease
this minimum requirement for any future Offering so long as the maximum number
of hours does not exceed 20 hours;



             (c) if specified by the Plan Administrator for future Offerings,
minimum requirements for customary employment of a maximum of five months per
year;

             (d) the employee has been employed for at least three months as of
the Offering Date; provided, however, if specified by the Plan Administrator for
any future Offering, a minimum employment period that does not exceed two years;
and

             (e) the employee is not a highly compensated employee. For purposes
of the Plan, a "highly compensated employee" is any employee of Immunex or a
Designated Subsidiary who has a base salary in excess of $175,000 per year;
provided, however, that the Plan Administrator may increase or decrease this
amount for any future Offering within the limitations imposed by Code Section
423.

If the Company permits any employee of a Designated Subsidiary to participate in
the Plan, then all employees of that Designated Subsidiary who meet the
requirements of this paragraph shall also be considered Eligible Employees.

     "Enrollment Period" has the meaning set forth in Section 7.1.

     "ESPP Broker" has the meaning set forth in Section 10.

     "ESPP Conversion Ratio" has the meaning set forth in Section 6.3.

     "Exchange Act" means the Securities Exchange Act of 1934, as amended.

     "Immunex" has the meaning set forth in Section 1.

     "Immunex Common Stock" means the common stock, par value $.01 per share, of
Immunex.

     "Merger Agreement" means the Amended and Restated Agreement and Plan of
Merger, by and between Amgen Inc., AMS Acquisition Inc. and Immunex Corporation,
dated as of December 16, 2001, as amended by that certain First Amendment to
Amended and Restated Agreement and Plan of Merger dated as of July 15, 2002.

     "Offering" has the meaning set forth in Section 5.1.

     "Offering Date" means the first day of an Offering.

     "Option" means an option granted under the Plan to an Eligible Employee to
purchase shares of Common Stock.

     "Parent Corporation" means any corporation, other than Immunex, in an
unbroken chain of corporations ending with Immunex, if, at the time of the
granting of the Option, each of the corporations, other than Immunex, owns stock
possessing 50% or more of the total combined voting power of all classes of
stock in one of the other corporations in such chain.

     "Participant" means any Eligible Employee who has elected to participate in
an Offering in accordance with the procedures set forth in Section 7.1 and who
has not withdrawn from the Plan or whose participation in the Plan is not
terminated.

     "Plan" has the meaning set forth in Section 1.

     "Plan Administrator" has the meaning set forth in Section 3.1.

                                        2



     "Purchase Date" means the last day of each Purchase Period.

     "Purchase Period" has the meaning set forth in Section 5.2.

     "Purchase Price" has the meaning set forth in Section 6.

     "Subscription" has the meaning set forth in Section 7.1.

     "Subsidiary Corporation" means any corporation, other than Immunex, in an
unbroken chain of corporations beginning with Immunex, if, at the time of the
granting of the Option, each of the corporations, other than the last
corporation in the unbroken chain, owns stock possessing 50% or more of the
total combined voting power of all classes of stock in one of the other
corporations in such chain.

SECTION 3.   ADMINISTRATION

     3.1     Plan Administrator

     The Plan shall be administered by the Board or the Committee or, if and to
the extent the Board or the Committee designates an executive officer of the
Company to administer the Plan, by such executive officer (each, the "Plan
Administrator"). Any decisions made by the Plan Administrator shall be
applicable equally to all Eligible Employees.

     3.2     Administration and Interpretation by the Plan Administrator

     Subject to the provisions of the Plan, the Plan Administrator shall have
the authority, in its sole discretion, to determine all matters relating to
Options granted under the Plan, including all terms, conditions, restrictions
and limitations of Options; provided, however, that all Participants granted
Options pursuant to the Plan shall have the same rights and privileges within
the meaning of Code Section 423. The Plan Administrator shall also have
exclusive authority to interpret the Plan and may from time to time adopt, and
change, rules and regulations of general application for the Plan's
administration. The Plan Administrator's interpretation of the Plan and its
rules and regulations, and all actions taken and determinations made by the Plan
Administrator pursuant to the Plan, unless reserved to the Board or the
Committee, shall be conclusive and binding on all parties involved or affected.
The Plan Administrator may delegate administrative duties to such of the
Company's other officers or employees as the Plan Administrator so determines.

SECTION 4.   STOCK SUBJECT TO PLAN

     Subject to adjustment from time to time as provided in Section 20, the
maximum number of shares of Common Stock which shall be available for issuance
under the Plan shall be 1,297,405/1/ shares. Shares issued under the Plan shall
be drawn from authorized and unissued shares or shares now held or subsequently
acquired by the Company.

- ------------
/1/ The original number of shares of Immunex Common Stock in the Plan was
500,000. This was adjusted to 3,000,000 as a result of a 2-for-1 stock split on
August 26, 1999 and a split March 20, 2000. This number was subsequently
adjusted to reflect the conversion of the shares of Immunex Common Stock that
remained available for issuance under the Plan as of the Effective Time (as
defined in the Merger Agreement) into shares of Common Stock in a manner
intended to comply with Section 424(a) of the Code.

                                        3



SECTION 5.  OFFERING DATES

      5.1   Offerings

      (a)       Except as otherwise set forth below, the Plan shall be
implemented by a series of Offerings (each, an "Offering"). Offerings shall
commence on May 1 and November 1 of each year and end on the next October 31 and
April 30, respectively, occurring thereafter (each, an "Offering").

      (b)       Notwithstanding the foregoing, the Plan Administrator may
establish (i) a different term for one or more Offerings and (ii) different
commencing and ending dates for such Offerings; provided, however, that an
Offering may not exceed five years; and provided, further, that if the Purchase
Price may be less than 85% of the fair market value of the Common Stock on the
Purchase Date, the Offering may not exceed one year.

      (c)       In the event the first or the last day of an Offering is not a
regular business day, then the first day of the Offering shall be deemed to be
the next regular business day and the last day of the Offering shall be deemed
to be the last preceding regular business day.

      5.2   Purchase Periods

            (a) Each Offering shall consist of one or more consecutive purchase
periods (each, a "Purchase Period"). The last day of each Purchase Period shall
be the Purchase Date for such Purchase Period. Each Purchase Period shall
commence on May 1 and November 1 of each year and end on the next October 31 and
April 30, respectively, occurring thereafter.

            (b) Notwithstanding the foregoing, the Board may establish (i) a
different term for one or more Purchase Periods and (ii) different commencing
and ending dates for any such Purchase Period.

            (c) In the event the first or last day of a Purchase Period is not a
regular business day, then the first day of the Purchase Period shall be deemed
to be the next regular business day and the last day of the Purchase Period
shall be deemed to be the last preceding regular business day.

      5.3   Governmental Approval; Stockholder Approval

     Notwithstanding any other provision of the Plan to the contrary, an Option
granted pursuant to the Plan shall be subject to (a) obtaining all necessary
governmental approvals and qualifications of the Plan and of the issuance of
Options and sale of Common Stock pursuant to the Plan and (b) obtaining
stockholder approval of the Plan.

SECTION 6.  PURCHASE PRICE

      6.1   General Rule

     Subject to Section 6.3, the purchase price at which Common Stock may be
acquired in an Offering pursuant to the exercise of all or any portion of an
Option granted under the Plan (the "Purchase Price") shall be 85% of the lesser
of (a) the fair market

                                        4



value of the Common Stock on the Offering Date of such Offering and (b) the fair
market value of the Common Stock on the Purchase Date.

      6.2   Fair Market Value

      The fair market value of the Common Stock on the Offering Date or on the
Purchase Date shall be the closing price for the Common Stock as reported for
such day by the Nasdaq Stock Market, the New York Stock Exchange or other
trading market on which the Company's Common Stock may then be traded (the
"Exchange"). If no sales of the Common Stock were made on the Exchange on such
day, fair market value shall mean the closing price for the Common Stock as
reported for the next preceding day on which sales of the Stock were made on the
Exchange. If the Common Stock is not listed on an Exchange, the Board shall
designate an alternative method of determining the fair market value of the
Common Stock.

      6.3   Purchase Period Ending on October 31, 2002

      Notwithstanding Section 6.1, the Purchase Price with respect to the
Purchase Period commencing on May 1, 2002 and ending on October 31, 2002 shall
be 85% of the lesser of (a) the quotient obtained by dividing (i) the closing
price on May 1, 2002 of a share of Immunex Common Stock as reported by the
Nasdaq Stock Market, by (ii) the ESPP Conversion Ratio (as defined below), and
(b) the fair market value of a share of Common Stock on the Purchase Date. For
purposes of the above calculation, "ESPP Conversion Ratio" shall mean the
quotient obtained by dividing (x) the average of the closing trading prices of a
share of Immunex Common Stock on the Nasdaq Stock Market for the twenty (20)
consecutive trading days ending at 4:00 p.m. New York time on the fifth business
day immediately preceding the Closing Date (as defined in the Merger Agreement)
by (y) the average of the closing trading prices of a share of Common Stock on
the Nasdaq Stock Market for the twenty (20) consecutive trading days ending at
4:00 p.m. New York time on the fifth business day immediately preceding the
Closing Date.

SECTION 7.  PARTICIPATION IN THE PLAN

      7.1   Initial Participation

      An Eligible Employee shall become a Participant on the first Offering Date
after satisfying the eligibility requirements and delivering to the Plan
Administrator during the enrollment period established by the Plan Administrator
(the "Enrollment Period") a subscription (the "Subscription"):

            (a) indicating the Eligible Employee's election to participate in
the Plan;

            (b) authorizing payroll deductions and stating the amount to be
deducted regularly from the Participant's pay; and

            (c) authorizing the purchase of Common Stock for the Participant in
each Purchase Period.

      An Eligible Employee who does not deliver a Subscription as provided above
during the Enrollment Period shall not participate in the Plan for that
Offering, and shall

                                        5



not participate in the Plan for any subsequent Offering unless such Eligible
Employee subsequently enrolls in the Plan by delivering a Subscription to the
Plan Administrator during the Enrollment Period for such subsequent Offering.
The Plan Administrator may, from time to time, change the Enrollment Period for
any future Offering as it deems advisable in its sole discretion for the proper
administration of the Plan.

     Except as provided in Section 7.2, an employee who becomes eligible to
participate in the Plan after an Offering has commenced shall not be eligible to
participate in such Offering but may participate in any subsequent Offering,
provided that such employee is still an Eligible Employee as of the commencement
of any such subsequent Offering. Eligible Employees may not participate in more
than one Offering at a time.

     7.2  Alternative Initial Participation

     Notwithstanding any other provisions of the Plan, the Board or the
Committee may provide for any future Offering that any employee of Immunex or
any Designated Subsidiary who first meets the requirements of subparagraphs (a)
through (c) of the paragraph "Eligible Employee" in Section 2 during the course
of an Offering shall, on a date or dates specified in the Offering which
coincides with the day on which such person first meets such requirements or
occurs on a specified date thereafter, receive an Option under that Offering
which Option shall thereafter be deemed to be a part of that Offering. Such
Option shall have the same characteristics as any Options originally granted
under that Offering, except that:

     (i)  the date on which such Option is granted shall be the "Offering Date"
          of such Option for all purposes, including determining the Purchase
          Price of such Option; provided, however, that if the fair market value
          of the Common Stock on the date on which such Option is granted is
          less than the fair market value of Common Stock on the first day of
          the Offering, then, solely for the purpose of determining the Purchase
          Price of such Option, the first day of the Offering shall be the
          "Offering Date" for such Option;

     (ii) the Purchase Period(s) for such Option shall begin on its Offering
          Date and end coincident with the remaining Purchase Date(s) for such
          Offering; and

     (c)  the Board or the Committee may provide that if such person first meets
          such requirements within a specified period of time before the end of
          a Purchase Period for such Offering, he or she will not receive any
          Option for that Purchase Period.

     7.3  Continued Participation

     A Participant shall automatically participate in the next Offering until
such time as such Participant withdraws from the Plan pursuant to Section 11.1
or 11.2 or terminates employment as provided in Section 12.

                                        6



SECTION 8. LIMITATIONS ON RIGHT TO PURCHASE SHARES

     8.1  Number of Shares Purchased

     Subject to Section 8.3, the maximum number of shares of stock that may be
offered to a Participant on any Offering Date shall be equal to $15,000 divided
by the fair market value of one share of Common Stock on the applicable Offering
Date. Further, no Participant shall be entitled to purchase Common Stock under
the Plan (or any other employee stock purchase plan that is intended to meet the
requirements of Code Section 423 sponsored by the Company, Immunex, a Parent
Corporation or a Subsidiary Corporation) with a fair market value exceeding
$15,000, determined as of the Offering Date for each Offering (or such other
limit as may be imposed by the Code), in any calendar year in which a
Participant participates in the Plan (or other employee stock purchase plan
described in this Section 8.1). For any future Offering, the Board or the
Committee may specify a maximum number of shares which may be purchased by any
Participant as well as a maximum aggregate number of shares which may be
purchased by all Participants pursuant to such Offering. In addition, for any
future Offering with more than one Purchase Date, the Board or the Committee may
specify a maximum aggregate number of shares which may be purchased by all
Participants on any given Purchase Date under the Offering.

     8.2  Pro Rata Allocation

     In the event the number of shares of Common Stock that might be purchased
by all Participants in the Plan exceeds the number of shares of Common Stock
available in the Plan, the Plan Administrator shall make a pro rata allocation
of the remaining shares of Common Stock in as uniform a manner as shall be
practicable and as the Plan Administrator shall determine to be equitable.
Fractional shares may not be issued under the Plan unless the Plan Administrator
determines otherwise for any future Offering.

     8.3  Purchase Period Ending on October 31, 2002

     Notwithstanding the first sentence of Section 8.1, the maximum number of
shares of Common Stock that may be offered to any Participant with respect to
the Purchase Period commencing on May 1, 2002 and ending on October 31, 2002
shall be equal to $15,000, divided by the following quotient: (a) the closing
price on May 1, 2002 of a share of Immunex Common Stock as reported by the
Nasdaq Stock Market, divided by (b) the ESPP Conversion Ratio.

SECTION 9. PAYMENT OF PURCHASE PRICE

     9.1  General Rules

     Subject to Section 9.12, Common Stock that is acquired pursuant to the
exercise of all or any portion of an Option may be paid for only by means of
payroll deductions from the Participant's Eligible Compensation. Except as set
forth in this Section 9, the amount of compensation to be withheld from a
Participant's Eligible Compensation during each pay period shall be determined
by the Participant's Subscription.

     9.2  Changes in Withholding

     Unless otherwise determined by the Plan Administrator for any future
Offering, a Participant may not elect to increase or decrease the amount to be
withheld from his or

                                       7



her Eligible Compensation for an Offering; provided, however, that if such
elections are permitted for any future Offering, notice of such elections must
be delivered to the Plan Administrator in such form and in accordance with such
terms as the Plan Administrator may establish for the Offering.

     9.3   Percent Withheld

     The amount of payroll withholding for each Participant for purchases
pursuant to the Plan during any pay period shall be at least 1% but shall not
exceed 15% of the Participant's Eligible Compensation for such pay period, but
in no event shall exceed $15,000 per calendar year. Amounts shall be withheld in
whole percentages only.

     9.4   Payroll Deductions

     Payroll deductions shall commence on the first payday following the
Offering Date and shall continue through the last payday of the Offering unless
sooner altered or terminated as provided in the Plan.

     9.5   Memorandum Accounts

     Individual accounts shall be maintained for each Participant for memorandum
purposes only. All payroll deductions from a Participant's compensation shall be
credited to such account but shall be deposited with the general funds of the
Company. All payroll deductions received or held by Immunex or the Company may
be used by Immunex or the Company for any corporate purpose.

     9.6   No Interest

     No interest shall be paid on payroll deductions received or held by Immunex
or the Company.

     9.7   Acquisition of Common Stock

     On each Purchase Date of an Offering, each Participant shall automatically
acquire, pursuant to the exercise of the Participant's Option, the number of
shares of Common Stock arrived at by dividing the total amount of the
Participant's accumulated payroll deductions for the Purchase Period by the
Purchase Price; provided, however, that the number of shares of Common Stock
purchased by the Participant shall not exceed the number of whole shares of
Common Stock so determined, unless the Plan Administrator has determined for any
future Offering that fractional shares may be issued under the Plan; and
provided, further, that the number of shares of Common Stock purchased by the
Participant shall not exceed the number of shares for which Options have been
granted to the Participant pursuant to Section 8.1.

     9.8   Refund of Excess Amounts

     Any cash balance remaining in the Participant's account at the termination
of each Purchase Period shall be refunded to the Participant as soon as
practical after the Purchase Date without the payment of any interest; provided,
however, that if the Participant participates in the next Purchase Period, any
cash balance remaining in the Participant's account shall be applied to the
purchase of Common Stock in the new Purchase Period, provided such purchase
complies with Section 8.1.

                                        8



     9.9    Withholding Obligations

     At the time the Option is exercised, in whole or in part, or at the time
some or all of the Common Stock is disposed of, the Participant shall make
adequate provision for federal and state withholding obligations of Immunex or
the Company, if any, that arise upon exercise of the Option or upon disposition
of the Common Stock. Immunex or the Company may withhold from the Participant's
compensation the amount necessary to meet such withholding obligations.

     9.10   Termination of Participation

     No Common Stock shall be purchased on behalf of a Participant on a Purchase
Date if his or her participation in the Offering or the Plan has terminated on
or before such Purchase Date.

     9.11   Procedural Matters

     The Company may, from time to time, establish (a) limitations on the
frequency and/or number of any permitted changes in the amount withheld during
an Offering, as set forth in Section 9.2, (b) an exchange ratio applicable to
amounts withheld in a currency other than U.S. dollars, (c) payroll withholding
in excess of the amount designated by a Participant in order to adjust for
delays or mistakes in the Company's processing of properly completed withholding
elections and (d) such other limitations or procedures as deemed advisable by
the Company in the Company's sole discretion that are consistent with the Plan
and in accordance with the requirements of Code Section 423.

     9.12   Leaves of Absence

     During leaves of absence approved by the Company (or by Immunex previous to
the Closing Date (as defined in the Merger Agreement)) and meeting the
requirements of the applicable Treasury Regulations promulgated under the Code,
a Participant may elect to continue participation in the Plan by delivering cash
payments to the Plan Administrator on the Participant's normal paydays equal to
the amount of his or her payroll deduction under the Plan had the Participant
not taken a leave of absence. Currently, the Treasury Regulations provide that a
Participant may continue participation in the Plan only during the first 90 days
of a leave of absence unless the Participant's reemployment rights are
guaranteed by statute or contract.

SECTION 10. COMMON STOCK PURCHASED UNDER THE PLAN

     10.1   ESPP Broker

     If the Plan Administrator designates or approves a stock brokerage or other
financial services firm (the "ESPP Broker") to hold shares purchased under the
Plan for the accounts of Participants, the following procedures shall apply.
Promptly following each Purchase Date, the number of shares of Common Stock
purchased by each Participant shall be deposited into an account established in
the Participant's name with the ESPP Broker. Each Participant shall be the
beneficial owner of the Common Stock purchased under the Plan and shall have all
rights of beneficial ownership in such Common Stock. A Participant shall be free
to undertake a disposition of the shares of Common Stock in his or her account
at any time, but, in the absence of such a

                                        9



disposition, the shares of Common Stock must remain in the Participant's account
at the ESPP Broker until the holding period set forth in Code Section 423 has
been satisfied. With respect to shares of Common Stock for which the holding
period set forth above has been satisfied, the Participant may move those shares
of Common Stock to another brokerage account of the Participant's choosing or
request that a stock certificate be issued and delivered to him or her.
Dividends paid in the form of shares of Common Stock with respect to Common
Stock in a Participant's account shall be credited to such account. A
Participant who is not subject to payment of U.S. income taxes may move his or
her shares of Common Stock to another brokerage account of his or her choosing
or request that a stock certificate be delivered to him or her at any time,
without regard to the Code Section 423 holding period.

         10.2  Notice of Disposition

         By entering the Plan, each Participant agrees to promptly give the
Company notice of any Common Stock disposed of within the later of one year from
the Purchase Date and two years from the Offering Date for such Common Stock,
showing the number of such shares disposed of and the Purchase Date and Offering
Date for such Common Stock. This notice shall not be required if and so long as
the Company has a designated ESPP Broker.

SECTION 11.    VOLUNTARY WITHDRAWAL

         11.1  Withdrawal From an Offering

         A Participant may withdraw from an Offering by signing and delivering
to the Plan Administrator a written notice of withdrawal on a form provided by
the Plan Administrator for such purpose. Such withdrawal must be elected at
least 10 days prior to the end of the Purchase Period for which such withdrawal
is to be effective or by any other date specified by the Plan Administrator for
any future Offering. If a Participant withdraws after the Purchase Date for a
Purchase Period of an Offering, the withdrawal shall not affect Common Stock
acquired by the Participant in any earlier Purchase Periods. Unless otherwise
indicated, withdrawal from an Offering shall not result in a withdrawal from the
Plan or any succeeding Offering therein. A Participant is prohibited from again
participating in the same Offering at any time upon withdrawal from such
Offering. The Company may, from time to time, impose a requirement that the
notice of withdrawal be on file with the Plan Administrator for a reasonable
period prior to the effectiveness of the Participant's withdrawal.

         11.2  Withdrawal From the Plan

         A Participant may withdraw from the Plan by signing a written notice of
withdrawal on a form provided by the Plan Administrator for such purpose and
delivering such notice to the Plan Administrator. Such notice must be delivered
at least 10 days prior to the end of the Purchase Period for which such
withdrawal is to be effective or by any other date specified by the Plan
Administrator for any future Offering. In the event a Participant voluntarily
elects to withdraw from the Plan, the Participant may not resume participation
in the Plan during the same Offering, but may participate in any subsequent
Offering under the Plan by again satisfying the definition of Eligible Employee.
The Company may impose, from time to time, a requirement that the notice of
withdrawal be

                                       10



on file with the Plan Administrator for a reasonable period prior to the
effectiveness of the Participant's withdrawal.

         11.3  Return of Payroll Deductions

         Upon withdrawal from an Offering pursuant to Section 11.1 or from the
Plan pursuant to Section 11.2, the withdrawing Participant's accumulated payroll
deductions that have not been applied to the purchase of Common Stock shall be
returned as soon as practical after the withdrawal, without the payment of any
interest, to the Participant and the Participant's interest in the Offering
shall terminate. Such accumulated payroll deductions may not be applied to any
other Offering under the Plan.

SECTION 12.    TERMINATION OF EMPLOYMENT

         Termination of a Participant's employment with Immunex or a Designated
Subsidiary or the Company for any reason, including retirement, death or any
other failure of a Participant to remain an employee of Immunex or a Designated
Subsidiary or the Company, shall immediately terminate the Participant's
participation in the Plan. The payroll deductions credited to the Participant's
account since the last Purchase Date shall, as soon as practical, be returned to
the Participant or, in the case of a Participant's death, to the Participant's
legal representative or designated beneficiary as provided in Section 13.2, and
all of the Participant's rights under the Plan shall terminate. Interest shall
not be paid on sums returned to a Participant pursuant to this Section 12.

SECTION 13.    RESTRICTIONS ON ASSIGNMENT

         13.1  Transferability

         An Option granted under the Plan shall not be transferable and such
Option shall be exercisable during the Participant's lifetime only by the
Participant. The Company will not recognize, and shall be under no duty to
recognize, any assignment or purported assignment by a Participant of the
Participant's interest in the Plan, of his or her Option or of any rights under
his or her Option.

         13.2  Beneficiary Designation

         The Plan Administrator may permit a Participant to designate a
beneficiary who is to receive any shares and cash, if any, from the
Participant's account under the Plan in the event the Participant dies after the
Purchase Date for an Offering but prior to delivery to such Participant of such
shares and cash. In addition, the Plan Administrator may permit a Participant to
designate a beneficiary who is to receive any cash from the Participant's
account under the Plan in the event that the Participant dies before the
Purchase Date for an Offering. Such designation may be changed by the
Participant at any time by written notice to the Plan Administrator.

SECTION 14.    NO RIGHTS AS STOCKHOLDER UNTIL SHARES ISSUED

         With respect to shares of Common Stock subject to an Option, a
Participant shall not be deemed to be a stockholder of the Company, and he or
she shall not have any of the rights or privileges of a stockholder. A
Participant shall have the rights and privileges of a stockholder of the Company
when, but not until, a certificate or its equivalent has been issued to the
Participant for the shares following exercise of the Participant's Option.

                                       11



SECTION 15. LIMITATIONS ON SALE OF COMMON STOCK PURCHASED UNDER THE PLAN

         The Plan is intended to provide Common Stock for investment and not for
resale. The Company does not, however, intend to restrict or influence any
Participant in the conduct of his or her own affairs. A Participant, therefore,
may sell Common Stock purchased under the Plan at any time he or she chooses,
subject to compliance with any applicable federal and state securities laws. A
Participant assumes the risk of any market fluctuations in the price of the
Common Stock.

SECTION 16. AMENDMENT OF THE PLAN

         The Board may amend the Plan in such respects as it shall deem
advisable; provided, however, that, to the extent required for compliance with
Code Section 423 or any applicable law or regulation, stockholder approval will
be required for any amendment that will (a) increase the total number of shares
as to which Options may be granted under the Plan, (b) modify the class of
employees eligible to receive Options, or (c) otherwise require stockholder
approval under any applicable law or regulation.

SECTION 17. TERMINATION OF THE PLAN

         The Plan shall have no fixed termination date. Notwithstanding the
foregoing, the Board may suspend or terminate the Plan at any time. During any
period of suspension or upon termination of the Plan, no Options shall be
granted; provided, however, that suspension or termination of the Plan shall
have no effect on Options granted prior thereto.

SECTION 18. NO RIGHTS AS AN EMPLOYEE

         Nothing in the Plan shall be construed to give any person (including
any Eligible Employee or Participant) the right to remain in the employ of
Immunex or any of its affiliates or to affect the right of Immunex or any of its
affiliates to terminate the employment of any person (including any Eligible
Employee or Participant) at any time with or without cause.

SECTION 19. EFFECT UPON OTHER PLANS

         The adoption of the Plan shall not affect any other compensation or
incentive plans in effect for Immunex or any of its affiliates. Nothing in this
Plan shall be construed to limit the right of Immunex or any of its affiliates
to (a) establish any other forms of incentives or compensation for employees of
Immunex or any of its affiliates or (b) grant or assume options otherwise than
under this Plan in connection with any proper corporate purpose, including, but
not by way of limitation, the grant or assumption of options in connection with
the acquisition, by purchase, lease, merger, consolidation or otherwise, of the
business, stock or assets of any corporation, firm or association.

SECTION 20. ADJUSTMENTS

         20.1 Adjustment of Shares

         In the event that, at any time or from time to time, a stock dividend,
stock split (but not including the stock dividend approved by the board of
directors of Immunex on February 23, 1999), spin-off, combination or exchange of
shares, recapitalization,

                                       12



merger, consolidation, distribution to stockholders other than a normal cash
dividend, or other change in the Company's corporate or capital structure
results in (a) the outstanding shares, or any securities exchanged therefor or
received in their place, being exchanged for a different number or kind of
securities of the Company or of any other corporation or (b) new, different or
additional securities of the Company or of any other corporation being received
by the holders of shares of Common Stock, then (subject to any required action
by the Company's stockholders), the Board or the Committee, in its sole
discretion, shall make such equitable adjustments as it shall deem appropriate
in the circumstances in (i) the maximum number and kind of shares of Common
Stock subject to the Plan as set forth in Section 4 and (ii) the number and kind
of securities that are subject to any outstanding Option and the per share price
of such securities. The determination by the Board or the Committee as to the
terms of any of the foregoing adjustments shall be conclusive and binding.
Notwithstanding the foregoing, a dissolution, liquidation, merger or asset sale
of the Company shall not be governed by this Section 20.1 but shall be governed
by Sections 20.2 and 20.3, respectively.

         20.2 Merger or Asset Sale of Immunex or the Company

         In the event of a proposed sale of all or substantially all of the
assets of Immunex or the Company, or the merger of Immunex or the Company with
or into another corporation (but not including any internal corporate
restructuring or reorganization involving Immunex and the Company), each
outstanding Option shall be assumed or an equivalent option substituted by the
successor corporation or a parent or subsidiary corporation of the successor
corporation. In the event that the successor corporation refuses to assume or
substitute for the Option, the Offering then in progress shall be shortened by
setting a new Purchase Date. The new Purchase Date shall be a specified date
before the date of the proposed sale or merger of Immunex or the Company. The
Board shall notify each Participant in writing, at least 10 business days prior
to the new Purchase Date, that the Purchase Date for the Participant's Option
has been changed to the new Purchase Date and that the Participant's Option
shall be exercised automatically on the new Purchase Date, unless prior to such
date the Participant has withdrawn from the Offering or the Plan as provided in
Section 11 hereof.

         20.3 Dissolution or Liquidation of Immunex or the Company

         In the event of the proposed dissolution or liquidation of Immunex or
the Company (but not including any internal corporate restructuring or
reorganization involving Immunex and the Company), the Offering then in progress
shall be shortened by setting a new Purchase Date and shall terminate
immediately prior to the consummation of such proposed dissolution or
liquidation, unless provided otherwise by the Board. The new Purchase Date shall
be a specified date before the date of the proposed dissolution or liquidation
of Immunex or the Company. The Board shall notify each Participant in writing,
at least 10 business days prior to the new Purchase Date, that the Purchase Date
for the Participant's Option has been changed to the new Purchase Date and that
the Participant's Option shall be exercised automatically on the new Purchase
Date, unless prior to such date the Participant has withdrawn from the Offering
or the Plan as provided in Section 11 hereof.

                                       13



         20.4 Limitations

         The grant of Options will in no way affect the Company's right to
adjust, reclassify, reorganize or otherwise change its capital or business
structure or to merge, consolidate, dissolve, liquidate or sell or transfer all
or any part of its business or assets.

SECTION 21. REGISTRATION; CERTIFICATES FOR SHARES

         The Company shall be under no obligation to any Participant to register
for offering or resale under the Securities Act of 1933, as amended, or register
or qualify under state securities laws, any shares of Common Stock. The Company
may issue certificates for shares with such legends and subject to such
restrictions on transfer and stop-transfer instructions as counsel for the
Company deems necessary or desirable for compliance by the Company with federal
and state securities laws.

SECTION 22. EFFECTIVE DATE

         The Plan's effective date is the date on which it was approved by
Immunex's shareholders, which was April 29, 1999. The Plan was amended and
restated by the board of directors of Immunex on April 25, 2000 and was amended
and restated by the Board on July 15, 2002.

                                       14

                                                                    EXHIBIT 10.4

                               IMMUNEX CORPORATION
                   STOCK OPTION PLAN FOR NONEMPLOYEE DIRECTORS
                     Amended and Restated on April 18, 2000

SECTION 1.  PURPOSES

     The purposes of the Immunex Corporation Stock Option Plan for Nonemployee
Directors (this "Plan") are to attract and retain the services of experienced
and knowledgeable nonemployee directors of Immunex Corporation (the "Company")
and to provide an incentive for such directors by providing an opportunity for
stock ownership in the Company.

SECTION 2.  SHARES SUBJECT TO THE PLAN

     Subject to adjustment in accordance with Section 6 hereof, the total number
of shares of the Company's common stock (the "Common Stock") for which options
may be granted under this Plan is 1,200,000/1/ (the "Shares"). The Shares shall
be shares currently authorized but unissued or subsequently acquired by the
Company and shall include shares representing the unexercised portion of any
option granted under this Plan which expires or terminates without being
exercised in full.

SECTION 3.  ADMINISTRATION OF THE PLAN

     The administrator of this Plan (the "Plan Administrator") shall be the
Board of Directors of the Company (the "Board"). Subject to the terms of this
Plan, the Plan Administrator shall have the power to construe the provisions of
this Plan, to determine all questions arising hereunder and to adopt and amend
such rules and regulations for the administration of this Plan as it may deem
desirable.

SECTION 4.  PARTICIPATION IN THE PLAN

     4.1    Eligible Directors

     Each member of the Board elected or appointed who is not otherwise an
employee of the Company, any parent or subsidiary corporation, or a director
appointed by American Cyanamid Company or American Home Products Corporation
pursuant to the Amended and Restated Governance Agreement dated as of December
15, 1992 (an "Eligible Director") shall be eligible to participate in this Plan.

____________
     /1/ The original number of Shares in this Plan was 100,000. This number was
adjusted to 1,200,000 as a result of a 2-for-1 stock split on March 25, 1999, a
2-for-1 stock split on August 26, 1999 and a 3-for-1 stock split on March 20,
2000.

                                                                          Page 1



     4.2   Initial Grants

     Each Eligible Director who is elected or appointed for the first time after
the date of adoption of this Plan shall automatically receive the grant of an
option to purchase 10,000 Shares on the day such Eligible Director is initially
elected or appointed.

     4.3   Annual Grants

     Each Eligible Director continuing service as an Eligible Director
immediately following an Annual Meeting of Shareholders shall automatically
receive an option to purchase 5,000 Shares immediately following each year's
Annual Meeting of Shareholders as an annual grant; provided, however, that an
Eligible Director who has received an initial grant of an option to purchase
10,000 Shares on such date shall not receive an annual grant until the next
Annual Meeting.

SECTION 5. OPTION TERMS

     Each option granted to an Eligible Director under this Plan and the
issuance of Shares hereunder shall be subject to the following terms:

     5.1   Option Agreement

     Each option granted under this Plan shall be evidenced by an option
agreement (an "Agreement") duly executed on behalf of the Company. Each
Agreement shall comply with and be subject to the terms and conditions of this
Plan. Any Agreement may contain such other terms, provisions and conditions not
inconsistent with this Plan as may be determined by the Plan Administrator.

     5.2   Option Exercise Price

     The option exercise price for an option granted under this Plan shall be
the closing price, or if there is no closing price, the mean between the high
and the low sale price of the Shares covered by the option on the day the option
is granted on the Nasdaq Stock Market or, if no Common Stock was traded on such
date, on the immediately preceding date on which Common Stock was so traded.

     5.3   Vesting and Exercisability

     Each option granted to an Eligible Director shall vest and become
exercisable in accordance with the following schedule:

 Period of Eligible Directors' Continuous
Service as a Director With the Company From     Portion of Total Option Which Is
   the Date the Option is Granted                         Exercisable
- ---------------------------------------------  ---------------------------------

      Less than twelve months                                 0%

                                                                          Page 2




            Twelve months                              20%

          Twenty-four months                           40%

          Thirty-six months                            60%

          Forty-eight months                           80%

       Sixty months or greater                        100%

     Notwithstanding the foregoing, for any Option granted under the Plan, the
Option shall become 100% vested and exercisable on the date of termination of an
Eligible Director's service as a member of the Board on account of the Eligible
Director's death, provided that the Eligible Director has served as a member of
the Board for at least two years at the date of such Eligible Director's death.

     5.4 Time and Manner of Exercise of Option

     Each option may be exercised in whole or in part at any time and from time
to time; provided, however, that no fewer than 100 Shares (or the remaining
Shares then purchasable under the option, if less than 100 Shares) may be
purchased upon any exercise of any option hereunder and that only whole Shares
will be issued pursuant to the exercise of any option.

     Any option may be exercised by giving written notice, signed by the person
exercising the option, to the Company stating the number of Shares with respect
to which the option is being exercised, accompanied by payment in full for such
Shares, which payment may be in whole or in part (a) in cash or by check, (b) in
shares of Common Stock already owned for at least six months by the person
exercising the option, valued at fair market value at the time of such exercise,
or (c) by delivery of a properly executed exercise notice, together with
irrevocable instructions to a broker, to properly deliver to the Company the
amount of sale or loan proceeds to pay the exercise price, all in accordance
with the regulations of the Federal Reserve Board.

     5.5 Term of Options

    Each option shall expire ten years from the date of the granting thereof,
but shall be subject to earlier termination as follows:

          (a)   In the event that an optionee ceases to be a director of the
     Company for any reason other than the death of the optionee the unvested
     portion of the options granted to such optionee shall terminate immediately
     and the vested portion of the options granted to such optionee may be
     exercised by him or her only within three months after the date such
     optionee ceases to be a director of the Company.

          (b)   In the event of the death of an optionee, whether during the
     optionee's service as a director or during the three month period referred
     to in Section 5.5(a), the unvested portion of the options granted to such
     optionee shall terminate immediately and the vested portion of the options
     granted to such optionee shall be exercisable, and such

                                                                          Page 3




     options shall expire unless exercised within twelve months after the date
     of the optionee's death, by the legal representatives or the estate of such
     optionee, by any person or persons whom the optionee shall have designated
     in writing on forms prescribed by and filed with the Company or, if no such
     designation has been made, by the person or persons to whom the optionee's
     rights have passed by will or the laws of descent and distribution.

     5.6  Transferability

     During an optionee's lifetime, an option may be exercised only by the
optionee. Options granted under this Plan and the rights and privileges
conferred thereby shall not be subject to execution, attachment or similar
process and may not be transferred, assigned, pledged or hypothecated in any
manner (whether by operation of law or otherwise) other than by will or by the
applicable laws of descent and distribution. In addition, the Plan Administrator
may permit a recipient of an option to designate in writing during the
optionee's lifetime a beneficiary to receive and exercise options in the event
of the optionee's death (as provided in Section 5.5(b)). Any attempt to
transfer, assign, pledge, hypothecate or otherwise dispose of any option under
this Plan or of any right or privilege conferred thereby, contrary to the
provisions of this Plan, or the sale or levy or any attachment or similar
process upon the rights and privileges conferred hereby, shall be null and void.

     5.7  Holding Period

     If an individual subject to Section 16 of the Exchange Act of 1934, as
amended (the "Exchange Act") sells shares of Common Stock obtained upon the
exercise of any option granted under this Plan within six months after the date
the option was granted, such sale may result in short-swing profit recovery
under Section 16(b) of the Exchange Act.

     5.8  Participant's or Successor's Rights as Shareholder

     Neither an optionee nor the optionee's successor(s) in interest shall have
any rights as a shareholder of the Company with respect to any Shares subject to
an option granted to the optionee until such person becomes a holder of record
of such Shares.

     5.9  Limitation as to Directorship

     Neither this Plan, nor the granting of an option, nor any other action
taken pursuant to this Plan shall constitute or be evidence of any agreement or
understanding, express or implied, that an optionee has a right to continue as a
director for any period of time or at any particular rate of compensation.

     5.10 Regulatory Approval and Compliance

     The Company shall not be required to issue any certificate or certificates
for Shares upon the exercise of an option granted under this Plan, or record as
a holder of record of Shares the name of the individual exercising an option
under this Plan, without obtaining to the complete satisfaction of the Plan
Administrator the approval of all regulatory bodies deemed necessary by

                                                                          Page 4



the Plan Administrator, and without complying, to the Plan Administrator's
complete satisfaction, with all rules and regulations under federal, state or
local law deemed applicable by the Plan Administrator.

SECTION 6. CAPITAL ADJUSTMENTS

     The aggregate number and class of Shares for which options may be granted
under this Plan, the number and class of Shares covered by each outstanding
option and the exercise price per Share thereof (but not the total price) shall
all be proportionately adjusted for any stock dividends, stock splits,
recapitalizations, combinations or exchanges of shares, split-ups, split-offs,
spinoffs, or other similar changes in capitalization. Notwithstanding the
foregoing, if an automatic grant occurs within ninety days following any such
change in capitalization, the aggregate number and class of Shares subject to
such automatic grant shall be proportionately adjusted to be the same number and
class of Shares that would be subject to the automatic grant had it been
outstanding immediately prior to the date of such change in capitalization. Upon
the effective date of a dissolution or liquidation of the Company, or of a
reorganization, merger or consolidation of the Company with one or more
corporations that results in more than 70% of the outstanding voting shares of
the Company being owned by one or more affiliated corporations or other
affiliated entities, or of a transfer of all or substantially all the assets or
more than 70% of the then outstanding shares of the Company to another
corporation or other entity, this Plan and all options granted hereunder shall
terminate. In the event of such dissolution, liquidation, reorganization,
merger, consolidation, transfer of assets or transfer of stock, each optionee
shall be entitled, for a period of twenty days prior to the effective date of
such transaction, to purchase the full number of shares under his or her option
which he or she otherwise would have been entitled to purchase during the
remaining term of such option.

     Adjustments under this Section 6 shall be made by the Plan Administrator,
whose determination shall be final. In the event of any adjustment in the number
of Shares covered by any option, any fractional Shares resulting from such
adjustment shall be disregarded and each such option shall cover only the number
of full Shares resulting from such adjustment.

SECTION 7. EXPENSES OF THE PLAN

     All costs and expenses of the adoption and administration of this Plan
shall be borne by the Company; none of such expenses shall be charged to any
optionee.

SECTION 8. COMPLIANCE WITH RULE 16b-3

     It is the intention of the Company that this Plan comply in all respects
with the requirements for a "formula plan" within the meaning attributed to that
term for purposes of Rule 16b-3 promulgated under Section 16(b) of the Exchange
Act. Therefore, if any Plan provision is later found not to be in compliance
with such requirements, that provision shall be deemed null and void, and in all
events this Plan shall be construed in favor of its meeting such requirements.

                                                                          Page 5



SECTION 9.   TERMINATION AND AMENDMENT OF THE PLAN

     The Board may amend, terminate or suspend this Plan at any time, in its
sole and absolute discretion; provided, however, that if required to qualify
this Plan as a formula plan for purposes of Rule 16b-3 under Section 16(b) of
the Exchange Act, no amendment may be made more than once every six months that
would change the amount, price, timing or vesting of the options, other than to
comply with changes in the Internal Revenue Code of 1986, as amended, or the
rules and regulations thereunder; provided further that no amendment that would
(a) increase the number of Shares that may be issued under this Plan, or (b)
otherwise require shareholder approval under any applicable law or regulation
shall be made without the approval of the Company's shareholders.

SECTION 10.  DURATION

     This Plan shall continue in effect until December 13, 2003 unless it is
sooner terminated by action of the Board or the Company's shareholders, but such
termination shall not affect the terms of any then-outstanding options. Adopted
by the Company's Board of Directors on December 13, 1993 and approved by the
Company's shareholders on April 27, 1994. Amended and restated by the Board on
February 13, 1997. Amended and restated by the Board on February 23, 1999.
Amended and restated by the Board on April 18, 2000.

                                                                          Page 6



                                    ADDENDUM
                                     TO THE
                               IMMUNEX CORPORATION
                   STOCK OPTION PLAN FOR NONEMPLOYEE DIRECTORS

     WHEREAS, Immunex Corporation (the "Company") maintains the Stock Option
Plan for Nonemployee Directors (the "Plan"); and

     WHEREAS, the Company desires to adjoin an addendum (this "Addendum") to the
Plan to address the effects of the transactions contemplated by the Agreement
and Plan of Merger by and between Amgen Inc., AMS Acquisition Inc. and the
Company dated as of December 16, 2001 (the "Merger Agreement");

     NOW, THEREFORE, notwithstanding anything in the Plan to the contrary, this
Addendum is hereby adopted, effective as of the Effective Time (as defined in
the Merger Agreement):

     Section 1. At the Effective Time, each option granted pursuant the Plan
shall be treated in accordance with the applicable terms of the Merger
Agreement.

     Section 2. In the event that an optionee ceases to be a director of the
Company or Amgen Inc. for any reason immediately prior to, at, or during the
fifteen (15) months following the Effective Time, each option held by such
optionee for common stock of Amgen Inc. shall immediately vest in full and shall
remain exercisable until the earlier of (x) the first anniversary of the date
such optionee ceases to be a director of the Company or Amgen Inc. or (y) the
end of the term of such option.

     Section 3. This Addendum shall be effective only upon the Effective Time.
In the event that the Merger Agreement terminates according to its terms, this
Addendum shall be of no force or effect.

                                                                    EXHIBIT 10.5

                               IMMUNEX CORPORATION

                      PROFIT SHARING 401(k) PLAN AND TRUST







               (As Amended and Restated Effective January 1, 2000)



                                    CONTENTS


                                                                         
I.   NAME AND EFFECTIVE DATE............................................... I-1
     1.1    Name........................................................... I-1
     1.2    Effective Date................................................. I-1

II.  DEFINITIONS........................................................... II-1
     2.1    Accounts....................................................... II-1
     2.2    Accrued Benefit................................................ II-1
     2.3    Affiliate...................................................... II-1
     2.4    Allocable Income............................................... II-1
     2.5    Beneficiary.................................................... II-1
     2.6    Board.......................................................... II-2
     2.6    Code........................................................... II-2
     2.7    Compensation................................................... II-2
     2.8    Computation Period............................................. II-3
     2.9    Employee....................................................... II-3
     2.10   Employer....................................................... II-4
     2.11   Enrollment Date................................................ II-4
     2.12   ERISA.......................................................... II-4
     2.13   Highly Compensated Employee.................................... II-4
     2.14   Hour of Service................................................ II-5
     2.15   Investment Fund................................................ II-7
     2.16   Investment Manager............................................. II-7
     2.17   Limitation Year................................................ II-7
     2.18   Nonhighly Compensated Employee................................. II-7
     2.19   Normal Retirement Age.......................................... II-8
     2.20   One-Year Break in Service...................................... II-8
     2.21   Participant.................................................... II-8


Immunex Corporation Profit Sharing 401(k) Plan anf Trust                  Page i




                                                                        
      2.22  Participant Elected Contribution.............................  II-8
      2.23  Plan or Trust................................................  II-8
      2.24  Plan Administrator or Committee..............................  II-8
      2.25  Plan Year....................................................  II-8
      2.26  Required Beginning Date......................................  II-8
      2.27  Salary Deferral Agreement....................................  II-9
      2.28  Section 402(g) Limit.........................................  II-9
      2.29  Spouse.......................................................  II-9
      2.30  Surviving Spouse.............................................  II-10
      2.31  Trust Fund or Fund...........................................  II-10
      2.32  Trustee......................................................  II-10
      2.33  Trust Fund or Fund...........................................  II-10
      2.34  Valuation Date...............................................  II-10
      2.35  Year of Service..............................................  II-10

III.  ELIGIBLE EMPLOYEES.................................................  III-1
      3.1   Participation................................................  III-1
      3.2   Participation on Reemployment................................  III-1
      3.3   Ineligible Employees.........................................  III-2
      3.4   Inactive Participants........................................  III-2
      3.5   End of Participation.........................................  III-3
      3.6   Qualified Military Service...................................  III-3

IV.   CONTRIBUTIONS......................................................  IV-1
      4.1   Participant Elected Contributions............................  IV-1
      4.2.  Employer Matching Contributions..............................  IV-5
      4.3.  Employer's Profit Sharing Contribution.......................  IV-6
      4.4   Employee Contributions.......................................  IV-6
      4.5   Nondiscrimination Test:  Matching Contributions
            and Employee Contributions...................................  IV-6
      4.6   Rollover Contributions.......................................  IV-8


Immunex Corporation Profit Sharing 401(k) Plan anf Trust                 Page ii




                                                                               
V.     PARTICIPANT ACCOUNTS AND CREDITING OF CONTRIBUTIONS......................  V-1
       5.1  Accounts............................................................  V-1
       5.2  Allocation and Crediting of Contributions...........................  V-1
       5.3  Valuation of Assets.................................................  V-2
       5.4  Adjustment of Participants' Accounts................................  V-2
       5.5  Limitation on Allocations...........................................  V-3
       5.6  Controlled Groups...................................................  V-5
       5.7  Protection of Accrued Benefits......................................  V-5
       5.8  Title to Assets in Trustee..........................................  V-5

VI.    INVESTMENT FUNDS.........................................................  VI-1
       6.1  Separate Funds......................................................  VI-1
       6.2  Participant Direction...............................................  VI-1
       6.3  Investment Results..................................................  VI-1
       6.4  Voting of Stock Held in Investment Funds............................  VI-1
       6.5  Voting of Employer Stock............................................  VI-1
       6.6  Tender of Employer Stock............................................  VI-2

VII.   PARTICIPANT LOANS........................................................  VII-1
       7.1  Loans to Participants...............................................  VII-1
       7.2  Accounting for Loans................................................  VII-4

VIII.  NONFORFEITABLE BENEFITS..................................................  VIII-1
       8.1  Nonforfeitable Interest.............................................  VIII-1
       8.2  Years of Service....................................................  VIII-1
       8.3  No Increase in Pre-break Vesting....................................  VIII-2
       8.4  Forfeitable Interests...............................................  VIII-2
       8.5  Distribution to Separated Participants..............................  VIII-4

IX.    RETIREMENT...............................................................  IX-1
       9.1  Retirement Age and Benefit..........................................  IX-1


Immunex Corporation Profit Sharing 401(k) Plan anf Trust                Page iii




                                                                               
X.     DEATH BENEFIT............................................................  X-1
       10.1  Death of Participant...............................................  X-1
       10.2  Payments Upon Failure to Designate Beneficiary.....................  X-1

XI.    DISABILITY BENEFIT.......................................................  XI-1
       11.1  Payment Due........................................................  XI-1
       11.2  "Permanently Disabled".............................................  XI-1

XII.   DISTRIBUTIONS AND WITHDRAWALS............................................  XII-1
       12.1  Distribution of Benefits...........................................  XII-1
       12.2  Required Distributions.............................................  XII-2
       12.3  Distributions to Minors and Incompetents...........................  XII-4
       12.4  Qualified Domestic Relations Orders................................  XII-4
       12.5  Hardship Distributions.............................................  XII-6
       12.6  Direct Rollover Distributions......................................  XII-8
       12.7  Waiver of 30-Day Election Period...................................  XII-9

XIII.  TOP HEAVY PROVISIONS.....................................................  XIII-1
       13.1  Applicability......................................................  XIII-1
       13.2  Definitions........................................................  XIII-1
       13.3  Minimum Contributions..............................................  XIII-4
       13.5  Benefits Under Different Plans.....................................  XIII-5

XIV.   PROVISION AGAINST ANTICIPATION...........................................  XIV-1

XV.    ADMINISTRATIVE COMMITTEE - NAMED FIDUCIARY AND ADMINISTRATOR.............  XV-1
       15.1  Appointment of Committee...........................................  XV-1
       15.2  Committee Action...................................................  XV-1
       15.3  Rights and Duties..................................................  XV-1
       15.4  Investments........................................................  XV-3
       15.5  Information, Reporting and Disclosure..............................  XV-3
       15.6  Independent Qualified Accountant...................................  XV-3


Immunex Corporation Profit Sharing 401(k) Plan anf Trust                 Page iv




                                                                              
         15.7   Standard of Care Imposed Upon the Committee.....................  XV-4
         15.8   Allocation and Delegation of Responsibility.....................  XV-4
         15.9   Bonding.........................................................  XV-5
         15.10  Claims Procedure................................................  XV-5
         15.11  Unclaimed Account Procedures....................................  XV-9
         15.12  Funding Policy..................................................  XV-10
         15.13  Indemnification.................................................  XV-10

XVI.     APPOINTMENT OF INVESTMENT MANAGER......................................  XVI-1
         16.1   Authority for Appointment.......................................  XVI-1
         16.2   Investment Manager Discretion...................................  XVI-1

XVII.    INVESTMENT OF TRUST FUNDS BY TRUSTEE...................................  XVII-1

XVIII.   POWERS AND DUTIES OF TRUSTEE...........................................  XVIII-1
         18.1   Powers of Trustee...............................................  XVIII-1
         18.2   Annual Accounts.................................................  XVIII-3
         18.3   Notices and Directions..........................................  XVIII-3
         18.4   Standard of Care Imposed Upon Trustee...........................  XVIII-4
         18.5   Trustee's Acknowledgment of Responsibility......................  XVIII-5

XIX.     CONSTRUCTION...........................................................  XIX-1

XX.      LIABILITY OF TRUSTEE...................................................  XX-1
         20.1   Actions of Trustee Conclusive...................................  XX-1
         20.2   Distributions by Trustee........................................  XX-1
         20.3   Expenses of Administration......................................  XX-1
         20.4   Indemnity of Trustee............................................  XX-1

XXI.     RESIGNATION OR REMOVAL OF TRUSTEE......................................  XXI-1
         21.1   Resignation.....................................................  XXI-1
         21.2   Removal.........................................................  XXI-1
         21.3   Settlement of Account...........................................  XXI-1


Immunex Corporation Profit Sharing 401(k) Plan anf Trust                  Page v




                                                                                 
XXII.    SUITS....................................................................  XXII-1

XXIII.   MERGERS AND CONSOLIDATIONS...............................................  XXIII-1

XXIV.    AMENDMENT AND TERMINATION OF PLAN........................................  XXIV-1
         24.1   Right to Amend and Terminate......................................  XXIV-1
         24.2   No Revesting......................................................  XXIV-1
         24.3   Exclusive Benefit of Participants.................................  XXIV-1
         24.4   Termination and Discontinuance of Contributions...................  XXIV-1

XXV.     RIGHT TO DISCHARGE EMPLOYEES.............................................  XXV-1

XXVI.    RETURN OF CONTRIBUTIONS..................................................  XXVI-1
         26.1   Mistake of Fact...................................................  XXVI-1
         26.2   Allowance of Deductibility........................................  XXVI-1

XXVII.   PUERTO RICO..............................................................  XXVII-2


Immunex Corporation Profit Sharing 401(k) Plan and Trust                 Page vi



                               IMMUNEX CORPORATION

                      PROFIT SHARING 401(k) PLAN AND TRUST

     THIS DOCUMENT, made and executed by Immunex Corporation, a Washington
corporation, hereinafter referred to as the "Employer":

                                   WITNESSETH

     WHEREAS, the Employer established its profit sharing plan effective as of
January 1, 1987 and to conform the plan to applicable law, the Employer intends
to amend the plan by complete restatement; and

     WHEREAS, the Employer intends that the plan and trust established hereunder
be qualified under Sections 401(a) and 401(k) of the Internal Revenue Code (the
"Code") and be exempt from federal income taxation under Section 501(a) of the
Code; and

     WHEREAS, the form of this plan and trust has been approved by the Employer;

     NOW, THEREFORE, it is agreed:

Immunex Corporation Profit Sharing 401(k) Plan and Trust



                           I.  NAME AND EFFECTIVE DATE

1.1  Name

     This Plan shall be known as the Immunex Corporation Profit Sharing 401(k)
     Plan and Trust.

1.2  Effective Date

     The original effective date of the Plan was January 1, 1987. Unless
     specifically provided otherwise, the effective date of this Agreement (and
     the amended and restated Plan set forth herein) shall be January 1, 2000.
     The benefit payable to or on behalf of a Participant included under the
     Plan in accordance with the following provisions shall not be affected by
     the terms of any amendment to the Plan adopted after such Participant's
     service with the Employer terminates, unless the amendment expressly
     provides otherwise.

Immunex Corporation Profit Sharing 401(k) Plan and Trust                Page I-1



                                II.  DEFINITIONS

Whenever used herein, unless the context clearly indicates otherwise, masculine,
feminine, and neuter words may be used interchangeably, singular shall mean the
plural and vice versa, and the following words and phrases shall have the
following meanings:

2.1  Accounts

     "Accounts" means the individual separate Accounts established by the Plan
     Administrator in the name of each Participant in accordance with the Plan.

2.2  Accrued Benefit

     "Accrued Benefit" means the balance of a Participant's Accounts including
     investment experience, as of the most recent Valuation Date, plus
     accumulated contributions since such date and less any distributions since
     such date.

2.3  Affiliate

     "Affiliate" means any member of a controlled group of corporations (within
     the meaning of Code Section 414(b), as modified in accordance with Code
     Section 415(h) for purposes of Sections 5.5 and 5.6), a group of trades or
     businesses under common control (within the meaning of Code Section 414(c),
     as modified in accordance with Code Section 415(h) for purposes of Sections
     5.5 and 5.6) or an affiliated service group (within the meaning of Code
     Section 414(m) or (o)) of which the Employer is a member.

2.4  Allocable Income

     "Allocable Income" means net income or net loss. To calculate Allocable
     Income for the Plan Year, the Plan Administrator will use a uniform
     nondiscriminatory method that reasonably reflects the manner used by the
     Plan to allocate income to the Participant's Accounts. Allocable Income
     will not be determined for the period between the end of the Plan Year and
     the date of distribution.

2.5  Beneficiary

     "Beneficiary" means the person or persons designated as such by a
     Participant in accordance with Article X.

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page II-1



2.6  Board

     "Board" means the Board of Directors of Immunex Corporation.

2.6  Code

     "Code" means the Internal Revenue Code of 1986, as amended.

2.7  Compensation

     Except as otherwise expressly modified by other provisions of the Plan,
     "Compensation" means an Employee's wages, salary, fees for professional
     services and other amounts received during the Plan Year (without regard to
     whether or not an amount is paid in cash) for personal services actually
     rendered in the course of employment with the Employer to the extent that
     such amounts are includible in gross income, including, but not limited to,
     overtime, bonuses and commissions, but excluding fringe benefits and
     reimbursements or other expense allowances under a nonaccountable plan (as
     defined in Treasury Regulation (S) 1.62-2(c)). Compensation shall not
     include Employer contributions to a plan of deferred compensation to the
     extent that, before the application of the Section 415 limitations to that
     plan, the contributions are not includible in the employee's gross income
     for the taxable year in which contributed; deductible Employer
     contributions to a simplified employee pension plan described in Code
     Section 408(k); distribution from a plan of deferred compensation,
     regardless of whether such amounts are includible in the employee's gross
     income when distributed; amounts realized from the exercise of a
     non-qualified stock option or when restricted stock (or property) held by
     an employee becomes freely transferable or is no longer subject to a
     substantial risk of forfeiture; amounts realized from the sale, exchange or
     other disposition of stock acquired under a qualified stock option; or any
     other amounts which receive special tax benefits. Notwithstanding the
     foregoing, (i) Compensation shall include amounts excludable from the
     Employee's gross income by reason of Code Section 125, 402(e)(3), 402(h) or
     403(b), and (ii) solely for purposes of Sections 2.27, 4.1A, 4.1E, 4.2A and
     5.2A, Compensation shall not include commissions or, effective March 1,
     2002, retention bonuses. Effective on and after January 1, 2001,
     Compensation shall also include amounts excludable from the Employee's
     gross income for qualified taxable fringe benefits pursuant to Code Section
     132(f)(4).

     A Participant's Compensation for any Plan Year shall not exceed the
     Compensation Limit in effect under Code Section 401(a)(17), as adjusted for
     increases in the cost-of-living in accordance with Code

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page II-2



     Section 401(a)(17)(B) for such Plan Year. The Compensation Limit in effect
     for any Plan Year is the Compensation Limit in effect at the beginning of
     that Plan Year. For a Plan Year of less than 12 months, the Compensation
     Limit is a prorated dollar amount, determined by multiplying the
     Compensation Limit by a fraction, the numerator of which equals the number
     of months in the short period and the denominator of which equals 12.

2.8  Computation Period

     "Computation Period" shall mean a twelve (12) consecutive month period
     designated for purposes of determining an Employee's Years of Service and
     One-Year Breaks in Service for benefit accrual and vesting as follows:

          Eligibility Computation Period shall mean the twelve (12) consecutive
          month period beginning on the date on which the Employee first
          completes an Hour of Service. The second and subsequent Eligibility
          Computation Periods shall be the Plan Year, beginning with the Plan
          Year that includes the first anniversary of the date on which the
          Employee first completed an Hour of Service. In the case of an
          Employee who incurs a One-Year Break in Service prior to becoming a
          Participant, a new Eligibility Computation Period shall begin on the
          date on which the Employee first completes an Hour of Service
          following such One-Year Break in Service. The second and subsequent
          Eligibility Computation Periods for such Employee shall be the Plan
          Year, beginning with the Plan Year that includes the first anniversary
          of the date on which the Employee first completed an Hour of Service
          following his reemployment.

          Accrual Computation Period shall mean the Plan Year.

          Vesting Computation Period shall mean the Plan Year.

2.9  Employee

     "Employee" means any person, including officers, in the service of the
     Employer. Employee shall not mean an independent contractor. Employee shall
     also mean any leased employee, within the meaning of Code Section 414(n),
     unless such leased employee is covered by a plan maintained by the leasing
     organization that meets the requirements of Code Section 414(n)(5)(B) and
     leased employees do not constitute more than 20 percent of the Employer's
     Nonhighly Compensated Employee work force.

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page II-3



2.10 Employer

     "Employer" means Immunex Corporation and any Affiliate that, with the
     consent of the Board, elects to adopt the Plan and any organization that
     acquires the Employer's business and adopts the Plan; provided, that for
     purposes of Article XV (Administrative Committee) and Article XXIV
     (Amendment and Termination of Plan), Employer means Immunex Corporation.

2.11 Enrollment Date

     "Enrollment Date" means the first day of any month and shall be the date on
     which the Employee commences participation in the Plan.

2.12 ERISA

     "ERISA" means the Employee Retirement Income Security Act of 1974, as
     amended.

2.13 Highly Compensated Employee

     A.   Effective for Plan Years beginning on and after January 1, 1997,
          "Highly Compensated Employee" means an Employee who:

          1.   Was a more than 5% owner of an Employer (applying the
               constructive ownership rules of Code Section 318) during the Plan
               Year or during the preceding 12-month period; or

          2.   For the preceding Plan Year (i) had Compensation in excess of
               $80,000 (as adjusted by the Commissioner of Internal Revenue for
               the relevant year); and (ii) if the Employer so elects, was in
               the top-paid group of Employees (i.e., the group consisting of
               the top 20% of the Employees when ranked on the basis of
               Compensation paid during such Plan Year).

     B.   A Highly Compensated Employee also includes a former Employee who must
          be treated as a Highly Compensated Employee for the relevant Plan Year
          pursuant to Regulation Section 1.414(q)-1T Q&A-4 and Notice 97-45.

     C.   The Employer and its Affiliates shall be treated as a single Employer
          for purposes of determining the number and identity of Highly
          Compensated Employees.

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page II-4



2.14 Hour of Service

     "Hour of Service" means the following:

     A.   Each hour for which an Employee is paid, or entitled to payment, for
          the performance of duties for the Employer during the applicable
          Computation Period.

     B.   Each hour for which an Employee is paid, or entitled to payment, by
          the Employer on account of a period of time during which no duties are
          performed (irrespective of whether the employment relationship has
          terminated) due to vacation, holiday, illness, incapacity (including
          disability), layoff, jury duty, military duty or leave of absence.

          Notwithstanding the preceding sentence,

          1.   No more than 501 Hours of Service shall be credited under this
               paragraph to an Employee on account of any single continuous
               period during which the Employee performs no duties (whether or
               not such period occurs in a single Computation Period);

          2.   An hour for which an Employee is directly or indirectly paid, or
               entitled to payment, on account of a period during which no
               duties are performed is not required to be credited to the
               Employee if such payment is made or due under an insured
               disability plan or a plan maintained solely for the purposes of
               complying with applicable worker's compensation, unemployment
               compensation, or disability insurance laws;

          3.   Hours of Service are not required to be credited for a payment
               that solely reimburses an Employee for medically related expenses
               incurred by the Employee; and

          4.   For purposes of this paragraph, a payment shall be deemed to be
               made by or due from the Employer, regardless of whether such
               payment is made by or due from the Employer directly or
               indirectly through a trust fund or insurer to which the Employer
               contributes or pays premiums, and, regardless of whether
               contributions made or due to the trust fund, insurer or other
               entity are for the benefit of particular Employees or are on
               behalf of a group of Employees in the aggregate.

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page II-5



     C.   Each hour for which back pay, irrespective of mitigation of damages,
          is either awarded or agreed to by the Employer. The same Hours of
          Service shall not be credited both under paragraph A or paragraph B,
          as the case may be, and under this paragraph C.

     D.   Each hour with which an Employee would normally be credited (or eight
          hours per normal working day if the Plan is unable to determine the
          Employee's hours) during the Employee's absence from work if the
          Employee's absence commences in a Plan Year beginning after December
          31, 1984, and the absence is because of the Employee's pregnancy, the
          birth of the Employee's child, or the placement of a child with the
          Employee in connection with the Employee's adoption of the child, or
          for the purpose of caring for such child for a period beginning
          immediately after the child's birth or placement. An Employee shall be
          credited with the Employee's Hours of Service determined under this
          paragraph D only for the purpose of determining whether the Employee
          has incurred a One-Year Break in Service and the number of Hours of
          Service credited to an Employee in connection with such pregnancy or
          placement shall not exceed 501. Hours of Service credited under this
          paragraph D shall be credited in the Computation Period in which the
          Employee's absence begins or in the next following Computation Period
          if the Hours of Service credited under this paragraph are not needed
          to prevent the Employee from incurring a One-Year Break in Service in
          the earlier Computation Period. The Plan Administrator may establish
          reasonable requirements for information to be furnished by the
          Employee to show that the Employee's absence is for a reason referred
          to under this paragraph and the number of days of such absence. The
          Employee shall be credited with the Employee's Hours of Service under
          this paragraph only if the Employee provides the required information
          on a timely basis.

     E.   Other than as specifically required under this Section, the
          determination of Hours of Service for reasons other than the
          performance of duties and the crediting of Hours of Service to
          Computation Periods shall be in accordance with Department of Labor
          Regulations (S) 2530.200b-2(b) and (c), and such rules are hereby
          incorporated by reference.

     F.   For purposes of eligibility and vesting, service with an Affiliate
          (while it is an Affiliate) shall be considered service with the
          Employer and Hours of Service shall be credited, in accordance with
          this Section, for such service. In addition, effective January 1,
          2002, for purposes of

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page II-6



          eligibility and vesting, individuals who are Employees of Greenwich
          Holdings Inc. on January 1, 2002 (or who transfer from service covered
          by the American Home Products Corporation Savings Plan to an Employer
          as a result of, and by the first September 30 following, Immunex
          Corporation's acquisition of Greenwich Holdings Inc.) will be credited
          with the service they had accrued as of December 31, 2001 (or, if
          later, as of the date they transfer to an Employer) under the American
          Home Products Corporation Savings Plan.

     G.   Hours of Service shall also be credited for all purposes under the
          Plan to a leased employee, as defined in Code Section 414(n), for such
          employee's service to the Employer as a leased employee.

2.15 Investment Fund

     "Investment Fund" means a separate portion of the Trust Fund established at
     the direction of the Plan Administrator to provide investment options for
     Participants.

2.16 Investment Manager

     "Investment Manager" means a person, insurance company, corporation,
     partnership or association which is appointed by the Plan Administrator to
     direct the investment and reinvestment of all or any portion of the Trust
     Fund and which qualifies as an "investment manager" under the provisions of
     Section 3(38) of ERISA.

2.17 Limitation Year

     "Limitation Year" shall mean the 12 consecutive month period corresponding
     to the Plan Year and shall be the 12 month period under which the limits of
     Code Section 415 are applied.

2.18 Nonhighly Compensated Employee

     "Nonhighly Compensated Employee" shall mean an Employee who is not a Highly
     Compensated Employee.

2.19 Normal Retirement Age

     "Normal Retirement Age" means age 65.

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page II-7



2.20 One-Year Break in Service

     "One-Year Break in Service" means a Vesting Computation Period during which
     an Employee fails to complete more than 500 Hours of Service.

2.21 Participant

     "Participant" means an Employee who satisfies the eligibility requirements
     of Article III and who commences participation in the Plan.

2.22 Participant Elected Contribution

     "Participant Elected Contribution" means the amounts designated by a
     Participant pursuant to Section 4.1 and contributed to the Plan by the
     Employer in lieu of payment of an equal amount directly to the Participant
     as compensation.

2.23 Plan or Trust

     "Plan" or "Trust" means this Profit Sharing 401(k) Plan and Trust Agreement
     and all subsequent amendments thereto.

2.24 Plan Administrator or Committee

     "Plan Administrator" or "Committee" means the Administrative Committee as
     appointed by Employer pursuant to Section 15.1.

2.25 Plan Year

     "Plan Year" means the twelve (12) consecutive month period ending on the
     last day of December. The Plan Year shall be the year on which the records
     of the Plan are kept.

2.26 Required Beginning Date

     Effective for Plan Years beginning on and after January 1, 1997, "Required
     Beginning Date" means April 1 of the calendar year following the later of
     the calendar year in which the Participant's Service terminates or the
     calendar year in which the Participant attains age 70 1/2; provided,
     however, that if a Participant is a 5% owner (as defined in Code Section
     416) with respect to the calendar year in which such Participant attains
     age 70 1/2, the Participant's Required Beginning Date is April 1 of the
     calendar year following such calendar year.

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page II-8



     (a)  Any Participant (other than a 5% owner) who attained age 70 1/2 in
          years after 1995 and before January 1, 2002 may elect by April 1 of
          the calendar year following the year in which the Participant attained
          age 70 1/2 (or by December 31, 1997, in the case of a Participant
          attaining age 70 1/2 in 1996) to defer distributions until April 1 of
          the calendar year following the calendar year in which the Participant
          retires. If no such election is made, the Participant will begin
          receiving distributions by the April 1 of the calendar year following
          the calendar year in which the Participant attained age 70 1/2 (or by
          December 31, 1997, in the case of a Participant attaining age 70 1/2
          in 1996.)

     (b)  Any Participant (other than a 5% owner) who attained age 70 1/2 in a
          year prior to 1997 may elect to stop distributions and recommence
          benefit payments by April 1 of the calendar year following the
          calendar year in which the Participant retires.

     A Participant shall be considered a 5% owner for the purpose of this
     Section 2.26 if such Participant is a 5% owner as defined in Code Section
     416(i) at any time during the Plan Year ending with or within the calendar
     year in which such owner attains age 70 1/2. Once minimum required
     distributions begin to a 5% owner, they must continue to be distributed
     even if the Participant ceased to be a 5% owner in a subsequent year.

2.27 Salary Deferral Agreement

     "Salary Deferral Agreement" means the written authorization of a
     Participant to the Employer to deduct from the Participant's Compensation
     an amount or percentage to be deferred as a Participant Elected
     Contribution in accordance with this Plan.

2.28 Section 402(g) Limit

     "Section 402(g) Limit" means the limitation in effect under Code Section
     402(g) for such calendar year.

2.29 Spouse

     "Spouse" means the lawful husband or wife of the Participant.

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page II-9



2.30 Surviving Spouse

     "Surviving Spouse" means the Participant's Spouse surviving at the date of
     the Participant's death.

2.31 Trust Fund or Fund

     "Trust Fund" or "Fund" means all contributions received by the Trustee for
     purposes of the Plan, the investment thereof, and the earnings and
     appreciation thereon, less payments made to carry out the Plan.

2.32 Trustee

     "Trustee" means Security Trust Company or such other person(s) or
     entity(ies) designated by the Board to serve as trustee of the Trust Fund.

2.33 Trust Fund or Fund

     "Trust Fund" or "Fund" means all property held in the Trust.

2.34 Valuation Date

     "Valuation Date" means the last day of each Plan Year and such other date
     or dates as may be designated by the Plan Administrator.

2.35 Year of Service

     "Year of Service" means:

     A.   Eligibility Service

          For purposes of determining an Employee's eligibility to participate
          in the Plan, Year of Service shall mean the completion of 1,000 or
          more Hours of Service during an Eligibility Computation Period.

     B.   Benefit Accrual Service

          For purposes of determining an Employee's benefit accrual, Year of
          Service shall mean the completion of 1,000 or more Hours of Service
          during an Accrual Computation Period while a Participant.

     C.   Vesting Service

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page II-10



          For purposes of determining an Employee's nonforfeitable interest in
          the Employee's Accrued Benefit, Year of Service shall mean the
          completion of 1,000 or more Hours of Service during a Vesting
          Computation Period.

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page II-11



                            III.  ELIGIBLE EMPLOYEES

3.1  Participation

     A.   Subject to the provisions of Sections 3.1B, 3.1C and 3.3, an Employee
          shall participate in this Plan on the Enrollment Date that coincides
          with or immediately follows the date on which the Employee first
          performs one Hour of Service with the Employer.

     B.   An Employee who is regularly scheduled to work less than twenty (20)
          hours per week shall participate in this Plan on the Enrollment Date
          that coincides with or immediately follows the date on which such
          Employee completes one Year of Eligibility Service or attains age
          twenty-one (21), whichever occurs later.

     C.   An Employee who is classified by the Employer as a temporary employee
          shall participate in this Plan on the Enrollment Date that coincides
          with or immediately follows the date on which such Employee completes
          one Year of Eligibility Service or attains age twenty-one (21),
          whichever occurs later.

     D.   An Employee who is participating in the Plan immediately prior to the
          effective date of this Agreement shall continue to participate in the
          Plan subject to the provisions hereunder.

3.2  Participation on Reemployment

     A.   Subject to the provisions of Section 3.3, a former Participant shall
          resume participation in the Plan upon the date of the Participant's
          reemployment by the Employer if the Participant had a nonforfeitable
          interest under the Plan to any Accrued Benefit derived from Employer
          contributions at the time of the Participant's earlier separation from
          service or the number of the Employee's consecutive One-Year Breaks in
          Service is fewer than the greater of five (5) or the aggregate number
          of the Employee's Years of Service prior to such Break.

     B.   A former Participant who does not resume participation under paragraph
          A of this Section shall be required to again complete the eligibility
          requirement of Section 3.1 before participating in the Plan.

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page III-1



3.3  Ineligible Employees

     Notwithstanding the provisions of Section 3.1 and Section 3.2, the
     following classes of Employees shall not participate in the Plan:

     A.   An Employee who is covered by a collective bargaining agreement
          between employee representatives and the Employer, unless the
          collective bargaining agreement specifically requires participation in
          this Plan. In applying the preceding sentence, the term "employee
          representatives" shall not include an organization of which more than
          one-half of the members are owners, officers, or executives of the
          Employer.

     B.   A leased employee, within the meaning of Code Section 414(n).

     C.   A non-resident alien with no U.S.-source income (within the meaning of
          Code Section 911(d)(2)) from the Employer.

     D.   A summer intern.

     E.   An individual who is not treated by the Employer as an employee for
          payroll tax purposes, but who is subsequently determined by a
          government agency, by the conclusion or settlement of threatened or
          pending litigation, or otherwise to be (or to have been) an Employee,
          unless and until the Plan Administrator provides that such individual
          is eligible to participate in the Plan (which eligibility shall be on
          a prospective basis only).

3.4  Inactive Participants

     In the event a Participant transfers to an ineligible class of employees,
     such Employee's participation in the Plan for purposes of benefit accrual
     shall cease as of the date of such transfer.

     In the event an ineligible Employee transfers to the eligible class, such
     Employee shall participate in the Plan immediately if the Employee is a
     former Participant or the Employee has previously satisfied the
     requirements of Section 3.1 and would have previously been admitted to
     participation if the Employee had been in the eligible class.

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page III-2



3.5  End of Participation

     Active participation ends upon suspension of contributions or termination
     of employment. Participation ends when the individual has no further
     account balances under the Plan.

3.6  Qualified Military Service

     Effective December 12, 1994, notwithstanding anything herein to the
     contrary, contributions, benefits and service credit with respect to
     qualified military service will be provided in accordance with Code Section
     414(u).

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page III-3



                                IV.  CONTRIBUTIONS

4.1  Participant Elected Contributions

     A.   Election to Defer Compensation

          Each Participant may elect, effective as of the first day of any month
          coincident with or following the Participant's Enrollment Date, by
          filing a Salary Deferral Agreement with the Plan Administrator within
          such time as the Plan Administrator may determine, to defer any whole
          percentage of the Participant's Compensation not to exceed 15% (20%
          for Plan Years beginning on or after January 1, 2002), but in any
          event, the amount of deferral shall not exceed the Section 402(g)
          Limit. Such deferred amounts shall be contributed to the Plan by the
          Employer and designated for such Participant's Deferral Account.
          Contributions shall be made by payroll deduction as authorized by the
          Participant on the Participant's Salary Deferral Agreement. The
          Participant may, in accordance with rules established by the Plan
          Administrator, increase or decrease his elective deferrals effective
          as of the first day of any month; provided, however, a Participant
          shall only be entitled to defer those amounts of Compensation that are
          not currently available to the Participant.

     B.   Payment to Trustee

          The Employer shall transmit the Participant Elected Contributions to
          the Trustee as soon as such Participant Elected Contributions can
          reasonably be segregated from the Employers' general assets, but in
          any event not later than the 15th business day of the month following
          the month in which such amounts would otherwise have been payable to
          the Participant in cash.

     C.   Limitation on Deferral of Compensation

          Effective for Plan Years beginning on and after January 1, 1997, the
          Participant Elected Contributions (together with any qualified
          nonelective contributions that the Plan Administrator may, under
          applicable Treasury Regulations, elect (and does elect) to include in
          the calculation) for a Plan Year shall satisfy one of the following
          tests:

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page IV-1



          1.   The Average Actual Deferral Percentage of the eligible Highly
               Compensated Employees for the current Plan Year may not be
               greater than the Average Actual Deferral Percentage of the
               eligible Nonhighly Compensated Employees for the prior Plan Year
               multiplied by 1.25; or

          2.   The Average Actual Deferral Percentage of the eligible Highly
               Compensated Employees for the current Plan Year may not be
               greater than the Average Actual Deferral Percentage of the
               eligible Nonhighly Compensated Employees for the prior Plan Year
               multiplied by 2. However, the excess of the Average Actual
               Deferral Percentage of the eligible Highly Compensated Employees
               for the current Plan Year over that of the eligible Nonhighly
               Compensated Employees for the prior Plan Year may not be greater
               than two (2.0) percentage points.

          The "Average Actual Deferral Percentage" for a specified group of
          Employees for a Plan Year shall be the average of the ratios
          (calculated separately for each Employee in such group) of the sum of
          the Participant Elected Contributions (and qualified nonelective
          contributions, if applicable) to the Employee's compensation, as
          defined under Code Section 414(s), for the entire Plan Year or
          compensation while the Participant was eligible to participate. The
          Plan Administrator shall select the Code Section 414(s) definition of
          compensation and the method to be used for the Plan Year and the same
          definition of compensation and method shall be applied to each
          Participant for that year.

          The Plan is subject to Code Section 401(k) and the regulations
          thereunder, which are hereby incorporated in this Document by
          reference. The above tests (and any necessary correction pursuant to
          Section 4.1D) shall be performed in accordance with such Code Section
          and regulations. In order to satisfy the above requirements, the Plan
          Administrator may, in its sole discretion, require the Employer to
          reduce future deferrals elected by the Highly Compensated Employees
          and/or return a portion of the amounts deferred by the Highly
          Compensated Employees in accordance with Section 4.1D.

          A Participant's Participant Elected Contribution shall be taken into
          account for a Plan Year for purposes of the foregoing tests only if it
          is considered allocated as of a date within that Plan Year. A
          Participant's

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page IV-2



          Participant Elected Contribution is considered allocated as of a date
          within the Plan Year only if:

          1.   The allocation is not contingent upon the Participant's
               participation in the Plan or performance of services on any date
               subsequent to that date; and

          2.   The elective contribution is actually paid to the Trust no later
               than the end of the twelve-month period immediately following the
               Plan Year to which the contribution relates.

          Likewise, a Participant's Participant Elected Contribution shall be
          taken into account for a Plan Year for purposes of the foregoing tests
          only if it relates to compensation that either:

          1.   Would have been received by the Participant in the Plan Year but
               for the Participant's election to defer; or

          2.   Is attributable to services performed by the Participant in the
               Plan Year and, but for the Participant's election to defer, would
               have been received by the Participant within two and one-half
               months after the close of the Plan Year.

          If an amount is returned to an Employee because the Employee's
          elective deferrals for the calendar year exceed the Section 402(g)
          Limit (other than excess elective deferrals of Nonhighly Compensated
          Employees that arise solely from elective deferrals made under the
          Plan or plans of the Employers), such excess deferrals shall
          nevertheless be counted in determining the Employee's actual deferral
          percentage for the Plan Year in which such excess deferrals were made.

          If two or more cash or deferred arrangements (as determined under Code
          Section 401(k)) are treated as a single plan for purposes of Code
          Sections 401(a)(4) or 410(b), such arrangements shall be treated as a
          single plan for purposes of the limitations of this Section.

     D.   Return of Excess Deferrals

          1.   Nondiscrimination Test

               If amounts contributed by the Employer for the Highly Compensated
               Employees cause the Plan to fail to meet the

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page IV-3



               requirements of Section 4.1C and Code Section 401(k) for a Plan
               Year, then, to the extent that such amounts are in excess of such
               limitations, the excess amounts (called excess contributions)
               shall be returned to the Highly Compensated Employees, together
               with Allocable Income, no later than the close of the following
               Plan Year. Excess contributions shall mean, with respect to any
               Plan Year, the excess of (a) the aggregate amount of Participant
               Elected Contributions (and qualified nonelective contributions,
               if applicable) actually taken into account in computing the
               Average Actual Deferral Percentage of the Highly Compensated
               Employees for such Plan Year, over (b) the maximum amount of such
               contributions permitted by the Average Actual Deferral Percentage
               test (determined by hypothetically reducing contributions made on
               behalf of Highly Compensated Employees in order of the actual
               deferral percentages, beginning with the highest of such
               percentages).

               The excess contributions are then allocated to the Highly
               Compensated Employees with the largest amounts of Participant
               Elected Contributions (and qualified nonelective contributions,
               if applicable) taken into account in calculating the Average
               Actual Deferral Percentage test for the Plan Year in which the
               excess arose, beginning with the Highly Compensated Employee with
               the largest amount of such contributions and continuing in
               descending order until all the excess contributions have been
               allocated. For purposes of the preceding sentence, the "largest
               amount" is determined after distribution of any excess
               contributions. The amount of excess contributions to be returned
               with respect to any Participant for a Plan Year shall be reduced
               by any excess deferrals previously distributed to such
               Participant for the Participant's taxable year ending with or
               within such Plan Year. The amount of excess deferrals that must
               be returned to a Participant for a taxable year shall be reduced
               by any excess contributions previously distributed with respect
               to such Participant for the Plan Year beginning with or within
               such taxable year of the Employer.

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page IV-4



          2.   Section 402(g) Limit

               If a Participant's elective deferrals (e.g., Participant Elected
               Contributions) under Code Section 401(k) exceed the Section
               402(g) Limit for a calendar year (such excess being called excess
               deferrals), the Plan Administrator shall distribute such excess
               deferrals, together with Allocable Income for the calendar year
               in which the excess deferrals were made, no later than April 15
               of the following calendar year. If a Participant makes elective
               deferrals under the Plan and under any other plan or arrangement
               described in Code Section 402(g)(3) for a Plan Year, and the
               total of such elective deferrals exceeds the Section 402(g)
               Limit, such Participant shall notify the Plan Administrator in
               writing on the prescribed form by March 1 of the succeeding Plan
               Year of the portion of the excess deferrals that he has allocated
               to the Plan and the Plan Administrator shall distribute the
               amount of excess deferrals allocated to this Plan, together with
               Allocable Income, to the Participant no later than April 15 of
               the calendar year following calendar year for which the excess
               deferrals were made.

     E.   Suspension of Deferrals

          A Participant may, upon thirty (30) days' prior written notice filed
          with the Plan Administrator, suspend the Participant's election under
          Section 4.1A to have a portion of the Participant's Compensation
          deferred. In the event of such a suspension, a Participant shall not
          be entitled to again elect to have Participant Elected Contributions
          made hereunder until the first day of the next month. The Participant
          shall, nevertheless, be considered a Participant hereunder for all
          other purposes during such period of time if the Participant's service
          with the Employer continues during that time.

4.2. Employer Matching Contributions

     A.   Basic Matching Contribution

          As soon as practicable following each pay period, the Employer shall
          make a contribution for each Participant who has Compensation deferred
          during that period and who is otherwise eligible, as provided in the
          following sentence, for such contributions. A Participant shall become
          eligible for contributions under this Section 4.2A as of the

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page IV-5



          January 1 or July 1 coincident with or next following the
          Participant's Enrollment Date. The contribution shall be equal to 100%
          of the first 2% of Compensation deferred by the Participant, plus, for
          Employees with less than five Years of Service, 50% of the amount
          deferred by the Participant that is between 2% and 6% of Compensation,
          and for Employees with five or more Years of Service, 75% of the
          amount deferred by the Participant that is between 2% and 6% of
          Compensation.

     B.   Forfeitures

          Forfeited amounts derived from the Employer Matching Account of a
          Participant who separates from the Employer's service shall be used to
          reduce the Employer's matching contribution for the Plan Year in which
          the forfeited amount becomes available and in subsequent years, if
          necessary.

4.3. Employer's Profit Sharing Contribution

     A.   Discretionary Contribution

          For any Plan Year, the Employer shall have the right to contribute an
          amount that the Employer, in its sole discretion, shall determine. The
          Employer's determination of its discretionary contribution shall be
          binding on all Participants, the Plan Administrator and the Employer.
          In making a discretionary contribution, the Employer shall have the
          discretionary authority to declare that a portion or all of the
          contribution for the Plan Year shall be a qualified nonelective
          contribution as defined in Code Section 401(m)(4)(C), which will be
          allocated as provided in Section 5.2C.

     B.   Date of Payment

          The Employer shall pay its discretionary contribution to the Trustee
          no later than the due date (including extensions thereof) for the
          filing of its federal income tax return for the fiscal year for which
          such contribution is made.

4.4  Employee Contributions

     Other than wage or salary deferrals allowed under Section 4.1A,
     contributions by an Employee under the Plan are not permitted.

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page IV-6



4.5  Nondiscrimination Test: Matching Contributions and Employee Contributions

     Effective for Plan Years beginning on and after January 1, 1997, in the
     case of Employer Matching Contributions and any other contributions that
     the Employer may elect to include as permitted under Treasury Regulations,
     such contributions shall satisfy one of the following tests:

     A.   The Average Contribution Percentage of the eligible Highly Compensated
          Employees for the current Plan Year shall be not greater than the
          Average Contribution Percentage of the eligible Nonhighly Compensated
          Employees for the prior Plan Year multiplied by 1.25; or

     B.   The Average Contribution Percentage of the eligible Highly Compensated
          Employees for the current Plan Year shall be not greater than the
          Average Contribution Percentage of the eligible Nonhighly Compensated
          Employees for the prior Plan Year multiplied by 2. However, the excess
          of the Contribution Percentage of the eligible Highly Compensated
          Employees for the current Plan Year over that of the eligible
          Nonhighly Compensated Employees for the prior Plan Year shall be not
          greater than two (2.0) percentage points.

     If a Highly Compensated Employee participates in a plan or plans maintained
     by the Employer or an Affiliate under which the Highly Compensated Employee
     is eligible to make elective contributions subject to the requirements of
     Code Section 401(k) and one or more of such plans is also subject to Code
     Section 401(m), the tests applied to the contributions for the Highly
     Compensated Employee shall be performed in accordance with Code Section
     401(m) and the regulations thereunder to prevent the multiple use of the
     alternative limitation as provided in Code Section 401(m).

     If two or more plans are aggregated for purposes of Code Section 410(b) or
     a Highly Compensated Employee participates in two or more plans of the
     Employer and its Affiliates to which matching contributions or employee
     after-tax contributions are made, all such contributions shall be
     aggregated to the extent required under Treasury Regulation (S)
     1.401(m)-1(f)(1)(ii)(B) to apply the requirements of this Section.

     The "Average Contribution Percentage" for a specified group of Employees
     for a Plan Year shall be the average of the ratios (calculated separately
     for each Employee in such group) of the sum of the Employer Matching
     Contributions (and such other contributions as permitted (or required) to
     be included in the

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page  IV-7



     calculation under Treasury Regulations) to the Employee's compensation, as
     defined under Code Section 414(s), for the entire Plan Year or compensation
     while the Participant was eligible to participate. The Plan Administrator
     shall select the Code Section 414(s) definition of compensation and the
     method to be used for the Plan Year and the same definition of compensation
     and method shall be applied to each Participant for that year.

     Contributions that cause the Average Contribution Percentage of the
     eligible Highly Compensated Employees to exceed the limits of this Section
     4.5 shall be distributed to the applicable Participant if vested, or
     forfeited if forfeitable, together with Allocable Income, before the close
     of the following Plan Year. Such excess contributions shall be called
     excess aggregate contributions. (The Employer will incur an excise tax
     equal to 10 percent of the amount of the excess aggregate contributions for
     a Plan Year that are not returned to the appropriate Highly Compensated
     Employees during the first 2-1/2 months of the following Plan Year.) Excess
     aggregate contributions shall mean, with respect to any Plan Year, the
     excess of (i) the aggregate amount of Employer Matching Contributions (and
     such other contributions as permitted (or required) to be included in the
     calculation under Treasury Regulations) actually taken into account in
     computing the Average Contribution Percentage of the Highly Compensated
     Employees for such Plan Year, over (ii) the maximum amount of such
     contributions permitted by the Average Contribution Percentage test
     (determined by hypothetically reducing contributions made on behalf of
     Highly Compensated Employees in order of the contribution percentages,
     beginning with the highest of such percentages). The excess aggregate
     contributions are then allocated to the Highly Compensated Employees with
     the largest amounts of Employer Matching Contributions (and such other
     contributions as permitted (or required) to be included in the calculation
     under Treasury Regulations) taken into account in calculating the Average
     Contribution Percentage test for the Plan Year in which the excess arose,
     beginning with the Highly Compensated Employee with the largest amount of
     such contributions and continuing in descending order until all the excess
     aggregate contributions have been allocated. For purposes of the preceding
     sentence, the "largest amount" is determined after distribution of any
     excess contributions. Forfeited amounts may not be reallocated to a Highly
     Compensated Employee whose contributions for such Plan Year are reduced by
     reason of this Section.

     Code Section 401(m) and the regulations thereunder are hereby incorporated
     in this Plan by reference and the limitations of this Section shall be
     carried out in accordance with such law and regulations.

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page  IV-8




4.6  Rollover Contributions

     A.   Subject to the approval of the Plan Administrator, the Plan may accept
          an "eligible rollover distribution," as defined in Section 12.6A, with
          respect to an Employee who is a Participant, or who is expected to
          become a Participant, provided, that the contribution is received on
          or before the 60th day following its distribution from the prior
          qualified plan or individual retirement account or as a direct
          rollover from the prior qualified plan.

     B.   Any rollover contribution accepted by the Plan shall be separately
          accounted for and the Participant shall have a nonforfeitable interest
          in such account called the Participant's Rollover Account at all
          times. The Participant's Rollover Account shall be adjusted with its
          pro rata share of net earnings, losses, appreciation, or depreciation
          as of each Valuation Date. If not earlier withdrawn, the total amount
          of a Participant's Rollover Account shall be paid to the Participant
          in the same form and at the same time as the Participant's
          Employer-derived Accrued Benefit.

     C.   If an Employee has not yet become a Participant at the time he makes a
          rollover contribution to the Plan, he shall be deemed to be a
          Participant only for purposes of the investment and distribution of
          such contribution. He shall not be permitted to make Participant
          Elected Contributions or share in Employer Matching Contributions or
          Employer Profit Sharing Contributions until he has become an active
          Participant pursuant to Article III.

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page  IV-9




             V. PARTICIPANT ACCOUNTS AND CREDITING OF CONTRIBUTIONS

5.1  Accounts

     The Plan Administrator shall establish in the name of each Participant such
     Accounts as are necessary to properly account for the types of
     contributions made on behalf of a Participant.

5.2  Allocation and Crediting of Contributions

     A.   Crediting of Participant Elected Contributions

          Employer contributions arising from a Participant's election to defer
          Compensation shall be credited to the Participant's Employee Deferral
          Account.

     B.   Crediting of Employer Matching Contributions

          Employer Matching Contributions shall be credited to the Employer
          Matching Account of the Participant for whom the Employer Matching
          Contribution is made in accordance with Section 4.2.

     C.   Allocation of the Employer's Profit Sharing Contribution

          A share of the Employer's Profit Sharing Contribution shall be
          allocated to the Employer Profit Sharing Account of a Participant who
          is in the service of the Employer on the last day of the Plan Year for
          which such contribution is made, who completes 1,000 or more Hours of
          Service during such Plan Year and who is otherwise eligible to share
          in such contribution, provided, that a Participant who retires after
          attaining Normal Retirement Age, dies, or becomes Permanently
          Disabled, as defined in Section 11.2, during the Plan Year shall share
          in the Employer's Profit Sharing Contribution for such Plan Year to
          the extent provided herein on the basis of the amount of the
          Participant's Compensation during such Plan Year prior to the
          Participant's termination of service. A Participant shall become
          eligible to share in the Employer's Profit Sharing Contributions as of
          the January 1 or July 1 coincident with or immediately following the
          Participant's Enrollment Date. In the case of a Participant who

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page  V-1



          otherwise qualifies for a Profit Sharing Contribution but who enters
          an ineligible class of Employees during the Plan Year, or in the case
          of a Participant who first becomes eligible to share in Profit Sharing
          Contributions during such Plan Year, such Participant shall share in
          the contributions for such Plan Year to the extent of the amount of
          the Participant's Compensation paid or accrued during the time the
          Participant was in an eligible class of employees and was eligible to
          share in the Employer's Profit Sharing Contribution for such Plan
          Year.

          The amount allocated to the Employer Profit Sharing Account of a
          Participant shall be a sum as shall bear the same ratio to the total
          contribution as the ratio such Participant's Compensation bears to the
          Compensation of all Participants eligible to share in the Profit
          Sharing Contribution.

          Forfeitable amounts derived from the Employer Profit Sharing Account
          of a Participant who separates from the Employer's service shall be
          used to reduce future Employer Matching Contributions.

          If the Employer designates some portion or all of its Profit Sharing
          Contribution as a qualified nonelective contribution, the qualified
          nonelective contribution shall be allocated among the Participants who
          are Nonhighly Compensated Employees based on the ratio that each such
          Participant's Compensation for the Plan Year bears to the Compensation
          of all such Participants for the Plan Year.

5.3  Valuation of Assets

     As of each Valuation Date, the Trustee shall value the assets of the Trust
     at the then current fair market value.

5.4  Adjustment of Participants' Accounts

     As of each Valuation Date, the net income (or loss) of the Trust since the
     immediately preceding Valuation Date shall be determined. Net income (or
     loss) of the Trust includes the increase (or decrease) in the fair market
     value of Trust Fund assets, interest income, dividends and other income and
     gains (or losses) attributable to Trust Fund assets since the immediately
     preceding Valuation Date, reduced by any expenses charged to the Trust Fund
     for the period since the immediately preceding Valuation Date.

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page  V-2




      The net income (or loss) of the Trust will be determined separately for
      each Investment Fund and allocated among the Accounts of the Participants
      in proportion to the respective balances of such Accounts invested in each
      such Investment Fund.

5.5   Limitation on Allocations

      Notwithstanding any other provision of the Plan, the annual addition to a
      Participant's Accounts for a Limitation Year shall not exceed an amount
      equal to:

      A.   Limitation. The lesser of:

           1.   $30,000, as adjusted pursuant to Code Section 415(d) for Plan
                Years beginning on and after January 1, 1995, or

           2.   Twenty-five percent (25%) of the compensation paid by the
                Employer to the Participant during the Limitation Year.
                Effective January 1, 1998, for purposes of this Section 5.5,
                compensation means Compensation as defined in Section 2.7.

      B.   Additions

           For purposes of imposing the limitations of Code Section 415, "annual
           additions" shall mean the sum of the following credited to the
           Participant for the Limitation Year:

           1.   Employer contributions;

           2.   The Participant's contributions other than a rollover
                contribution;

           3.   Forfeitures;

           4.   Amounts allocated to a separate account under a pension or
                annuity plan for a key employee (as defined under Code Section
                416(i)) in Plan Years beginning after March 31, 1984, to provide
                post-retirement medical benefits to such Participant and the
                Participant's spouse and dependents, and amounts paid after
                December 31, 1985, in tax years ending after that date to a
                separate account under a welfare benefit plan (as defined under
                Code Section 419(e)) of the Employer for a Participant who is or
                was a key employee (as defined under Code Section 416(i)) to
                provide post-retirement medical benefits to such Participant;
                and

Immunex Corporation Profit Sharing 401(k) Plan and Trust                Page V-3



           5.   Amounts allocated to a separate account under a pension or
                annuity plan for a Participant and the Participant's spouse and
                dependents, under which benefits described in Code Section
                401(h) are payable.

      C.   Aggregation of Plans

           All defined contribution plans maintained by the Employer, including
           voluntary employee contribution accounts in a defined benefit plan,
           Key employee accounts under a welfare benefit plan described in Code
           Section 419, and any Employer contributions allocated to an
           individual retirement account, shall be treated as a single plan for
           purposes of the limitations of this Section.

      D.   Excess Addition

           If the annual addition to the Account of a Participant exceeds the
           limitation of this Section 5.5 during a Plan Year, then such excess
           amount shall be eliminated first by returning, to the extent
           necessary to satisfy these limitations, the Participant's Participant
           Elected Contributions for such Plan Year, as adjusted for allocable
           income (together with forfeiting any related Matching Contribution),
           and then (if the limitations of this Section are still not satisfied)
           by reducing, to the extent necessary to satisfy these limitations,
           the Employer's contribution to the Participant's Account made for any
           other reason. The amount of the reduction (hereafter called the
           excess amount) shall be used to reduce the Employer's contribution
           for the next Plan Year, and each succeeding Plan Year, for that
           Participant if covered by the Plan as of the end of such Plan Year.
           If the Participant is not covered by the Plan as of the end of the
           Plan Year, then the excess amount shall be held unallocated in a
           suspense account for the Plan Year and allocated and reallocated in
           the next Plan Year, to the extent possible, to reduce the Employer's
           contribution for such Plan Year. If a suspense account is in
           existence during a Plan Year, other than the Plan Year in which it is
           established, the Employer shall make no contribution to the Plan
           until all amounts in the suspense account have been allocated and
           reallocated to Participants. No investment gains or losses or other
           income or expense shall be allocated to a suspense account. In the
           event a suspense account is in existence at the time the Plan
           terminates, any amount in the suspense account that cannot then be
           allocated to Participants shall be returned to the Employer.

Immunex Corporation Profit Sharing 401(k) Plan and Trust                Page V-4



5.6   Controlled Groups

      In applying the limitations of Section 5.5, the Employer and its
      Affiliates shall be treated as a single employer.

5.7   Protection of Accrued Benefits

      With the exception of an amendment described under Code Section 412(c)(8),
      no amendment to the Plan shall reduce the Accrued Benefit of a Participant
      determined as of the date immediately preceding the adoption of the
      amendment. In the event that an amendment either directly or indirectly
      reduces or restricts a protected benefit under Code Section 411(d)(6),
      such benefit for a Participant is presumed as of the later of the adoption
      date or the effective date of the amendment. In the case of an amendment
      adopted after July 30, 1984 that, with respect to benefits attributable to
      service before the amendment, eliminates or reduces an early retirement
      benefit or a retirement-type subsidy (as defined by the Secretary of the
      Treasury), such amendment shall not reduce the Accrued Benefit of a
      Participant, determined immediately prior to the adoption of the amendment
      and determined without regard to the amendment, if the Participant, either
      before or after the amendment but before termination of service, satisfies
      the preamendment requirements for the benefit. An amendment described in
      the preceding sentence shall not eliminate optional benefit forms (except
      as permitted by the Secretary of the Treasury) with respect to the Accrued
      Benefit of a Participant accrued as of the date immediately preceding the
      adoption of the amendment. The availability of any protected benefit of a
      Participant provided under the Plan, as defined in Code Section 411(d)(6),
      shall not be subject to the Employer's consent or discretion.

5.8   Title to Assets in Trustee

      Title to all assets under the Plan shall be vested in the Trustee which
      shall hold the Trust Fund and the income as a part thereof and make
      payments therefrom as provided in the Plan.

Immunex Corporation Profit Sharing 401(k) Plan and Trust                Page V-5



                              VI. INVESTMENT FUNDS

6.1   Separate Funds

      The Plan Administrator, in its discretion, shall select Investment Funds
      to be offered to Participants for investment of their Accounts, and the
      Plan Administrator shall direct the Trustee to establish accounts for the
      Investment Funds as determined by the Plan Administrator.

6.2   Participant Direction

      In the event that the Plan Administrator authorizes the use of more than
      one Investment Fund, each Participant shall designate the percentage of
      the future contributions to be allocated to his Accounts that will be
      invested in each of the Investment Funds available under the Plan. Any
      such designation shall be made in such increments, in such manner and
      pursuant to such other rules and limitations as the Plan Administrator
      shall prescribe. A Participant's investment designation shall remain in
      effect until changed by the Participant (or the Beneficiary, if
      applicable). A Participant (or Beneficiary, as applicable) may change his
      investment designation with respect to the future contributions to be
      allocated to, and/or the existing balances in, his Accounts at such times,
      in such increments and pursuant to such other rules and limitations as the
      Plan Administrator shall prescribe.

6.3   Investment Results

      As of each Valuation Date, the investment results obtained in the
Investment Funds shall be allocated only to the Account balances of Participants
who have invested in the fund.

6.4   Voting of Stock Held in Investment Funds

      With respect to each Participant's investment in any Investment Fund,
other than the Immunex Corporation Common Stock Fund, the Trustee shall vote the
number of shares credited to each Participant's Account, in each case, in a
manner that the Trustee believes to be consistent with its fiduciary duties
under section 404 of ERISA.

6.5   Voting of Employer Stock

      With respect to each Participant's investment in the Immunex Corporation
Common Stock Fund, before each annual or special meeting of the stockholders of
the

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page VI-1



Employer, the Employer will furnish such Participant with a copy of the proxy
solicitation material for such meeting, together with a form addressed to the
Trustee requesting the Participant's confidential instructions on how the shares
of Immunex Corporation common stock ("Shares") allocated to the Participant's
Account should be voted on each matter to come before the meeting. The number of
Shares allocated to a Participant's Account will be determined by multiplying
the number of Shares held in the Immunex Corporation Common Stock Fund as of the
applicable record date by a fraction, the numerator of which is the number of
units of such Fund held in the Participant's Account as of the applicable record
date and the denominator of which is the total number of outstanding units of
such Fund as of such date. Upon receipt of such instructions, the Trustee shall
vote Shares allocated to each Participant's Account (including fractional as
well as whole Shares) in accordance with timely directions of such Participant;
provided, that a failure of a Participant to timely and affirmatively direct the
manner in which Shares allocated to the Participant's Account are to be voted
shall be deemed for purposes of this Section to be an affirmative direction to
abstain from voting.

6.6   Tender of Employer Stock

      The Trustee shall, with respect to Shares allocated to that portion of
each Participant's Account invested in the Immunex Corporation Common Stock
Fund, act in response to any tender offer or exchange offer for Shares commenced
by a person or persons, including, but not limited to, a tender offer or
exchange offer within the meaning of the Securities Exchange Act of 1934, as
amended from time to time (all such tender or exchange offers collectively, a
"tender offer"), in accordance with timely directions of such Participant;
provided, that a failure of a Participant to timely and affirmatively direct the
manner in which the Trustee is to act in response to a tender offer with respect
to Shares allocated to the Participant's Account shall be deemed for purposes of
this Section to be an affirmative direction not to take action with respect to
such Shares. For purposes of determining the number of Shares to be the subject
of any particular response to a tender offer, the Trustee shall use the nearest
practicable date as determined by the Trustee. The number of Shares allocated to
a Participant's Account will be determined by multiplying the number of Shares
held in the Immunex Corporation Common Stock Fund as of the relevant date by a
fraction, the numerator of which is the number of units of such Fund held in the
Participant's Account as of such date and the denominator of which is the total
number of outstanding units of such Fund as of such date. The Employer and the
Trustee each shall use its best efforts to timely distribute or to cause to be
distributed to each Participant such information as is being distributed to
other stockholders of the Employer in connection with any such tender offer.

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page VI-2



                             VII. PARTICIPANT LOANS

The Plan Administrator, upon the application of a Participant, may direct the
Trustee to make a loan or loans to such Participant. The Plan Administrator
shall follow a uniform and nondiscriminatory policy in approving such loans and
loans shall be made available to Participants on a reasonably equivalent basis.

7.1   Loans to Participants

      A.  Availability of Loans

          Upon application by a Participant, the Plan Administrator may direct
          the Trustee to make a loan to the Participant from the vested balances
          in the Participant's Employee Deferral Account, Rollover Account and
          Employer Matching Account. Such borrowing rules must be formulated and
          administered so that the requirements of Code Section 72(p) for
          non-taxable loans, the applicable Department of Labor regulations on
          plan loans, and the following provisions of this Section 7.1 are
          satisfied. Any loan hereunder will bear a reasonable rate of interest
          and will be evidenced by a promissory note signed by the Participant
          in such form as the Plan Administrator may require. The amount of any
          such loan will be withdrawn from the vested balances in the
          Participant's Employee Deferral Account, Rollover Account and Employer
          Matching Account and from the Investment Fund or Funds in which such
          Accounts are invested in the manner specified in the Plan
          Administrator's borrowing rules.

      B.  Plan Administrator's Borrowing Rules

          The Plan Administrator may adopt borrowing rules for loans hereunder
          and may revise such rules from time to time. The rules may contain
          such requirements pertaining to loans as the Plan Administrator deems
          necessary or desirable and that are not specified herein. The
          borrowing rules may govern the procedures and cut-off dates for
          applying for loans hereunder and the terms of such loans, including
          (i) the number of loans that a Participant may request in any year and
          the number of loans that may be outstanding at any time to a
          Participant, (ii) any restrictions on reborrowing not stated in this
          Section 7.1, (iii) the interest rate in effect from time to time for
          loans or the method of ascertaining such interest rate, and (iv) the
          repayment schedule for loans or the method for determining the
          repayment schedule.

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page VII-1



      C.  Amount of Loans

          The minimum loan amount is $1,000 or such lesser amount as the Plan
          Administrator may from time to time set forth in its borrowing rules.
          The maximum aggregate loan amount is based upon the vested balances in
          the Participant's Accounts. No Participant loan will exceed the
          smallest of (i) the amount of the vested balances in the Participant's
          Employee Deferral Account, Rollover Account and Employer Matching
          Account, (ii) one-half of the Participant's vested Account balances,
          or (iii) $50,000 (reduced by the highest outstanding loan balance to
          the Participant during the 12 months preceding the loan). For purposes
          of applying such limits, Account values as the Valuation Date
          coincident with or immediately preceding the date on which the loan is
          made will be used.

      D.  Maximum Repayment Period

          1.   Other Than Residential Loans

               Except as provided in paragraph 2 immediately below, the maximum
               term of a loan will be 5 years (provided that the Plan
               Administrator may establish a shorter repayment period for small
               loans).

          2.   Residential Loans

               If a Participant requests a loan for the acquisition or
               construction of the Participant's principal residence, the
               repayment period will be determined by reference to bank loans
               for the same purpose but may not exceed 10 years; provided,
               however, that effective January 1, 2002, loans described in this
               paragraph 2 that are transferred (or rolled over) to this Plan
               from another plan shall retain the original term of such loan,
               even if it exceeds 10 years.

      E.  Security for Repayment

               Each loan hereunder will be a Participant-directed investment for
               the benefit of the Participant requesting such loan; accordingly,
               any default in the repayment of principal or interest of any loan
               hereunder will reduce the amount available for distribution to
               such Participant (or the Participant's Beneficiary). Thus, any
               loan hereunder will be secured by up to 50 percent of the vested
               amount in the Participant's Accounts. The

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page VII-2



          Plan Administrator acting under its borrowing rules may require other
          security for repayment of a loan in any instance. A Participant
          receiving a loan must execute such instruments as the Plan
          Administrator requests and must pay any fees for filings required by
          the Plan Administrator to perfect any security interest in the
          Participant's Accounts or other security.

      F.  Repayment

          The Plan Administrator may require a Participant to execute an
          agreement to repay the principal and interest of a loan through
          regular payroll deduction payments from the Participant's
          compensation. The Plan Administrator may establish back-up repayment
          procedures for Participants who do not make payroll deduction
          repayment. Except as otherwise may be permitted under Treasury
          regulations, any repayment procedure must provide for substantially
          level amortization payments made quarterly or more frequently. Any
          loan hereunder may be prepaid, in whole or in part, at any time
          without penalty. If a Participant's service as an Employee is
          terminated for any reason, the entire unpaid principal and interest of
          any loan then outstanding to such Participant will become immediately
          due and payable.

      G.  Action Upon Default

          If a Participant defaults on any payment of interest or principal of a
          loan hereunder or defaults upon any other obligation relating to such
          loan, the Plan Administrator may take (or direct the Trustee to take)
          such action or actions as it determines to be necessary to protect the
          interests of the Plan. Such actions may include commencing legal
          proceedings against the Participant, or foreclosing on any security
          interest in the Participant's Accounts or other security given in
          connection with a loan hereunder; however, the Plan Administrator will
          not direct foreclosure on the Participant's Employee Deferral Account
          at a time when the Participant would not be entitled to receive a
          distribution or withdrawal from such Account.

      H.  Distribution to Participant With Loan

          In the case of any Participant with a loan outstanding hereunder, the
          amount available for distribution to such Participant (or such
          Participant's Beneficiary) will consist of the portion of his Accounts
          invested in the Investment Funds of the Trust Fund. In addition, the

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page VII-3



          Participant's note will be distributed to the Participant (or the
          Participant's Beneficiary), and the Trustee will report the value of
          the note for income tax purposes as the amount of unpaid principal and
          interest due thereon at the date of distribution.

7.2   Accounting for Loans

      A.  Source of Loan

          The Plan Administrator will establish procedures and ordering rules
          for liquidating the Participant's Accounts to make a loan to him.

      B.  Loan Account

          The Plan Administrator will establish and maintain a loan account for
          each borrowing Participant. The unpaid principal and accrued but
          unpaid interest on the loans to a Participant will be reflected for
          Plan accounting purposes in the Participant's loan account. Repayments
          by the Participant will be credited to the Participant's loan account.
          The Plan Administrator will establish uniform procedures for
          transferring repayment amounts from his loan account to the
          Participant's other accounts.

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page VII-4



                          VIII. NONFORFEITABLE BENEFITS

8.1   Nonforfeitable Interest

      A Participant shall have a nonforfeitable interest in the Participant's
      Accounts based on the Participant's Years of Service for vesting. The
      Participant's Years of Service shall be determined in accordance with
      Section 8.2, and the Participant's nonforfeitable interest shall be
      determined as follows:

      A.  Employee Deferral Account and Rollover Account

          A Participant shall have a nonforfeitable interest in the
          Participant's Employee Deferral Account and Rollover Account at all
          times.

      B.  Employer Matching Account and Employer Profit Sharing Account

          A Participant's nonforfeitable interest in the Participant's Employer
          Matching Account and Employer Profit Sharing Account shall be
          determined under the following schedule:

         Completed Years                           Nonforfeitable
           of Service                                Percentage

          Less than 1                                     0
        1 but less than 2                                20
        2 but less than 3                                40
        3 but less than 4                                60
        4 but less than 5                                80
          5 or more                                     100

          In the event the Employer designates some part or all of a Profit
          Sharing Contribution for a Plan Year as a qualified nonelective
          contribution, a Participant to whom such a contribution is allocated
          shall have nonforfeitable interest in such contribution at all times.

8.2   Years of Service

      The following rules shall be applied in determining the number of a
      Participant's Years of Service using the Vesting Computation Period to
      credit Years of Service and One-Year Breaks in Service. All of an
      Employee's Years

Immunex Corporation Profit Sharing 401(k) Plan and Trust             Page VIII-1



     of Service with the Employer shall be counted except the following Years of
     Service shall be disregarded:

     A.   Years of Service prior to a One-Year Break in Service until the
          Employee completes a Year of Service following the Participant's
          return to the service of the Employer.

     B.   Years of Service completed prior to a One-Year Break in Service if the
          Employee does not have any nonforfeitable interest under the Plan to
          an Accrued Benefit derived from Employer contributions and the number
          of the Employee's consecutive One-Year Breaks in Service equals or
          exceeds the greater of five (5) or the aggregate number of the
          Employee's Years of Service prior to such Break; provided, that in the
          case of Plan Years beginning prior to January 1, 1985, a nonvested
          Employee's Years of Service prior to a One-Year Break in Service
          (incurred in a Plan Year beginning prior to 1985) shall not be counted
          if the number of the Employee's consecutive One-Year Breaks in Service
          equals or exceeds the aggregate number of the Employee's Years of
          Service prior to such Break. In applying the rules of this paragraph,
          if any Years of Service are disregarded by reason of any earlier
          One-Year Break in Service, such Years of Service shall not be
          aggregated when determining whether Years of Service are to be
          disregarded by reason of a subsequent One-Year Break in Service.

8.3  No Increase in Pre-break Vesting

     In the case of a Participant who incurs five (5) consecutive One-Year
     Breaks in Service, Years of Service completed by such Participant after
     such Break period shall not be counted to increase the Participant's
     nonforfeitable interest in the Participant's Accounts as determined prior
     to such Break period.

8.4  Forfeitable Interests

     Upon separation from the Employer's service for any reason, a Participant's
     forfeitable interest in the Participant's Accrued Benefit shall be
     forfeited in accordance with the following rules, whichever is applicable.

Immunex Corporation Profit Sharing 401(k) Plan and Trust             Page VIII-2



     A.   Zero Percent Vested

          In the event a Participant's service with the Employer terminates and
          such Participant does not have any nonforfeitable interest in the
          Participant's Accrued Benefit, the Participant shall be deemed to have
          received a distribution of such nonforfeitable Accrued Benefit on his
          termination date and the forfeitable portion of the Accrued Benefit
          shall be forfeited at the time of the Participant's separation from
          service. A Participant who has no vested interest will be deemed
          cashed out from the Plan. If a Participant is deemed to receive a
          distribution in accordance with this paragraph and the Participant
          resumes service with the Employer or an Affiliate before the date on
          which the Participant incurs five consecutive One-Year Breaks in
          Service, the amount of the forfeited Accrued Benefit shall be
          restored.

     B.   Partially Vested

          1.   Five-Year Break in Service

               In the event a Participant's service with the Employer and its
               Affiliates terminates and such Participant has a nonforfeitable
               interest in the Participant's Accrued Benefit but is not paid the
               entire nonforfeitable portion of the Participant's Account, a
               separate account shall be established for the Participant's
               remaining Accrued Benefit and the forfeitable interest the
               Participant shall be forfeited as of the end of the Plan Year in
               which the Participant incurs five (5) consecutive One-Year Breaks
               in Service. The Participant's nonforfeitable interest in the
               Participant's separate Account at any time prior to incurring 5
               consecutive One-Year Breaks in Service shall be an amount "X"
               determined under the formula X = P(AB + (R x D)) - (R x D), where
               P is the vested percentage at the relevant time; AB is the
               Account balance at the relevant time; D is the amount of the
               distribution; R is the ratio of the Account balance at the
               relevant time to the Account balance after distribution; and the
               relevant time is the time at which, under the Plan, the vested
               percentage in the Account cannot increase.

          2.   Cash Out Rule

               In the event a Participant's service with the Employer and its
               Affiliates terminates and such Participant is paid the
               Participant's

Immunex Corporation Profit Sharing 401(k) Plan and Trust             Page VIII-3



               entire nonforfeitable interest prior to incurring 5 consecutive
               One-Year Breaks in Service, the forfeitable interest of the
               Participant shall be forfeited at the time the payment is made.
               If the Participant returns to the Employer's (or an Affiliate's)
               service before incurring 5 consecutive One-Year Breaks in Service
               and repays to the Plan the full amount of the earlier
               distribution, the forfeited amount, unadjusted by any investment
               increases or decreases, shall be restored to the Participant's
               Account. To obtain a restoration of a forfeited amount, the
               Participant's repayment must be made before the earlier of the
               date on which the Participant incurs five consecutive One-Year
               Breaks in Service or the end of the five year period beginning
               with the date on which the Participant resumes employment with
               the Employer or an Affiliate. If the Participant's earlier
               distribution was made for any reason other than separation of
               service with the Employer and its Affiliates, the forfeited
               amount shall be restored only if the Participant repays the
               earlier distribution before the date five years after the date of
               the distribution. A Participant whose entire nonforfeitable
               interest has been distributed from the Plan will be deemed cashed
               out from the Plan.

8.5  Distribution to Separated Participants

     In the case of a Participant who separates from the service of the Employer
     and its Affiliates, the Participant's nonforfeitable interest in the
     Participant's Accounts shall be payable in accordance with the provisions
     of Article XII.

Immunex Corporation Profit Sharing 401(k) Plan and Trust             Page VIII-4



                                 IX. RETIREMENT

9.1   Retirement Age and Benefit

      A.  Normal Retirement

          A Participant shall have a nonforfeitable interest in the
          Participant's Accrued Benefit upon attaining Normal Retirement Age.
          Payment of the Participant's Accounts shall be made in accordance with
          the provisions of Article XII.

      B.  Postponed Retirement

          A Participant may not be required to retire involuntarily under this
          Plan simply because the Participant attains Normal Retirement Age.
          Subject to Section 12.2A, no payment of a Participant's Accounts shall
          be made under the Plan until a Participant actually retires and ceases
          employment. Upon actual retirement, payment of the Participant's
          Accounts shall be made in accordance with the provisions of Article
          XII.


Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page IX-1



                                X. DEATH BENEFIT

10.1      Death of Participant

          A Participant who dies while in the service of the Employer shall be
          100 percent vested in the Participant's Accounts upon the
          Participant's death. Upon a Participant's death, the nonforfeitable
          portion of the Participant's Accounts shall be payable to the
          Participant's Surviving Spouse, or the Participant's designated
          Beneficiary if the Participant has no Surviving Spouse at the time of
          death or the Spouse consents to the designation of a Beneficiary other
          than the Surviving Spouse. The designation of a Beneficiary to whom
          the Spouse has consented shall not be changed without the Spouse's
          consent to such change unless the Spouse's earlier consent expressly
          permits designations by the Participant without any requirement of
          further consent by the Spouse. A Spouse's consent must be in writing,
          it must acknowledge the effect of the Beneficiary designation and it
          must be witnessed by a notary public or a Plan representative. A
          Spouse's consent to a Beneficiary designation as provided for under
          this Section is effective only with respect to that Spouse. Payment of
          the death benefit shall be made in accordance with the provisions of
          Article XII, provided that the Surviving Spouse may require that the
          payment be made within a reasonable time following the Participant's
          death.

10.2      Payments Upon Failure to Designate Beneficiary

          Any portion of the amount payable that is undisposed of because of the
          failure to designate a Beneficiary or the failure of the Beneficiary
          to survive the Participant shall be paid in order of survivorship to:

          A.   The Participant's Surviving Spouse;

          B.   The Participant's descendants, per stirpes; and

          C.   If none are surviving, the Participant's estate.

          Notwithstanding the above, if the Plan Administrator is unable to
          locate any of the persons listed in (A) or (B) within three (3)
          months, the Plan Administrator may pay the death benefits to the
          Participant's estate.


Immunex Corporation Profit Sharing 401(k) Plan and Trust                Page X-1





                             XI.  DISABILITY BENEFIT

11.1 Payment Due

     If a Participant becomes Permanently Disabled while in the service of the
     Employer, the Participant shall be 100 percent vested in the Participant's
     Accounts as of the date of the Participant's disability. Payment of the
     Participant's entire interest shall be made in accordance with the
     provisions of Article XII.

11.2 "Permanently Disabled"

     "Permanently Disabled" means that the Participant is unable by reason of
     any medically determinable physical or mental impairment to substantially
     perform the regular material duties of the same occupations for which the
     Participant has been employed by the Employer, and such disability is
     expected to be of long, continued and indefinite duration. Permanent
     disability shall be established by the certification of a physician,
     selected by the Participant and approved by the Plan Administrator that the
     Participant has suffered a permanent disability, or if the physician
     selected by the Participant shall not be approved by the Plan
     Administrator, by a majority of three physicians, one selected by the
     Participant (or the Participant's Spouse, child, parent or legal
     representative in the event of the Participant's inability to select a
     physician), one by the Plan Administrator, and the third by the two
     physicians selected by the Participant and the Plan Administrator. The
     decision of the majority of such three physicians shall be final and
     conclusive.

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page XI-1



                       XII.  DISTRIBUTIONS AND WITHDRAWALS

12.1 Distribution of Benefits

     A.   Forms of Distribution

          Subject to subsection C below, any amounts payable under the terms of
          the Plan with respect to a Participant who retires after attaining
          Normal Retirement Age, becomes Permanently Disabled or dies shall, at
          the election of the Participant or Beneficiary (as applicable), be
          paid as a single-sum distribution of cash, or in a series of payments
          over a period not to extend beyond the life expectancy of the
          Participant (or the Beneficiary, as applicable) or the joint life
          expectancy of the Participant and the Participant's Beneficiary. Any
          amounts payable under the terms of the Plan with respect to a
          Participant who separates from service for any other reason shall be
          paid as a single-sum distribution of cash. No annuities shall be
          payable from the Plan. Each optional form of benefit offered under the
          Plan shall be available to all Participants on a nondiscriminatory
          basis. Notwithstanding the foregoing, if the Plan Administrator
          establishes an Investment Fund that is designed to invest primarily in
          the common stock of Immunex Corporation, a Participant (or
          Beneficiary, as applicable) may elect to receive such whole shares of
          Immunex Corporation common stock as are allocated to that portion of
          the Participant's vested Accounts that is invested in such Investment
          Fund (with cash for any fractional shares), in lieu of receiving cash
          for such portion of the Participant's Accounts.

     B.   Time of Distribution

          1.   Distribution Dates

               Subject to paragraph 2 of this subsection B, subsection C below
               and Section 12.2, benefits due to a Participant or Beneficiary,
               as applicable, shall be paid or commence to be paid within an
               administratively reasonable time following the Valuation Date
               elected by the Participant or Beneficiary, as applicable. A
               Participant or Beneficiary may elect to commence distributions as
               of any Valuation Date coinciding with or following the
               Participant's separation from service with the Employer and its
               Affiliates. In the case of a payment to a Participant, the
               payment shall not be made without the consent of the Participant,
               to the

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page XII-1



               extent required by law, if the value of the Participant's
               nonforfeitable interest in the Participant's Accounts exceeds
               $5,000 as of the date of distribution.

          2.   Consent to Distribution

               Unless a Participant elects in writing to receive the
               Participant's benefit at a later date, payment to a Participant
               shall be made no later than sixty (60) days after the close of
               the Plan Year in which the latest of the following events occurs:

               a.   The Participant attains age sixty-five (65);

               b.   The 10th anniversary of the date on which the Participant
                    first became a Participant; or

               c.   The termination of the Participant's service with the
                    Employer.

     C.   Small Benefit Cash-Out

          If the Participant's nonforfeitable interest in his Accounts does not
          exceed $5,000 as of the date of distribution, that interest shall be
          distributed as a lump sum within an administratively reasonable time
          following the Valuation Date coinciding with or immediately following
          the Participant's separation from service with the Employer and its
          Affiliates.

     D.   Valuation of Accounts for Distribution

          For purposes of determining the value of a Participant's Accounts
          under this Section, the value shall be determined as of the Valuation
          Date immediately preceding the date of distribution.

12.2 Required Distributions

     Notwithstanding any other provision of this Plan to the contrary, effective
     for Plan Years beginning on and after January 1, 1997, the following shall
     apply:

     A.   The entire interest of a Participant shall be distributed commencing
          no later than the Participant's Required Beginning Date.

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page XII-2



     B.   The Participant's interest shall be distributed over a period that
          does not exceed the life expectancy of the Participant (or the
          Beneficiary) or the life expectancy of the Participant and the
          Participant's designated Beneficiary, provided, that if the
          distributions are for a period measured by the life expectancy of the
          Participant or the joint life expectancy of the Participant and the
          Participant's Spouse, if applicable, such life expectancies shall be
          recalculated annually, if the Participant so elects. If the
          Participant's designated Beneficiary is someone other than his Spouse,
          then the Participant's life expectancy may be recalculated, but the
          Beneficiary's may not. Distributions to the Participant or the
          Participant and the Participant's designated Beneficiary shall meet
          the minimum annual distribution requirements and the incidental death
          benefit rules of Code Section 401(a)(9) and the regulations
          thereunder, including Treasury Regulation (S) 1.401(a)(9)-2, which are
          incorporated herein by reference.

          Notwithstanding any provision of the Plan to the contrary, with
          respect to distributions under the Plan made for calendar years
          beginning on or after January 1, 2001, the Plan will apply the minimum
          distribution requirements of Code Section 401(a)(9) in accordance with
          the regulations under Code Section 401(a)(9) that were proposed on
          January 17, 2001, notwithstanding any provision of the Plan to the
          contrary. This amendment shall continue in effect until the end of the
          last calendar year beginning before the effective date of final
          regulations under Code Section 401(a)(9) or such other date as may be
          specified in guidance published by the Internal Revenue Service.

     C.   If payments have commenced to the Participant and the Participant dies
          before the Participant's entire interest is distributed, the
          Participant's remaining interest shall be distributed to the
          Participant's Beneficiary at least as rapidly as under the method of
          distribution to the Participant as of the date of the Participant's
          death.

     D.   If a Participant dies before distribution of the Participant's
          interest has commenced, the Participant's entire interest shall be
          distributed by December 31 of the calendar year containing the fifth
          anniversary of the Participant's death, provided, that if the
          Participant has designated a Beneficiary to receive a part or all of
          the Participant's interest and if payment to the Beneficiary commences
          no later than December 31 of the calendar year following the year of
          the Participant's death, the portion payable to such Beneficiary may
          be paid over a period that does

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page XII-3



          not exceed the Beneficiary's life expectancy. In the event the
          Participant's designated Beneficiary is the Participant's Spouse,
          payment to the Spouse need not commence earlier than the later of
          December 31 of the year in which the Participant would have attained
          age seventy and one-half (70-1/2) or December 31 of the year following
          the year of the Participant's death. If a deceased Participant's
          designated Beneficiary is the Participant's Spouse and the Spouse dies
          before payments commence, the Participant's entire interest shall be
          distributed by applying the rules of this paragraph as though the
          deceased Spouse were the Participant.

12.3 Distributions to Minors and Incompetents

     If any Participant or Beneficiary entitled to receive benefits hereunder is
     a minor or, in the judgment of the Plan Administrator, unable to take care
     of his affairs because of mental condition, illness or accident, any
     payment due such person may, in the sole discretion of the Plan
     Administrator (unless prior claim therefor shall have been made by a
     qualified guardian or other legal representative), be paid for the benefit
     of such Participant or Beneficiary: (a) to such person's legal
     representative appointed by proceedings satisfactory to the Plan
     Administrator; (b) to such person (other than a minor) directly even though
     he is not then able to exercise control over such payment; and/or (c) to
     any custodian under the Uniform Gifts to Minors Act or similar statutes or
     guardian of such person or of his property with whom such person is making
     his home. Neither the Trustee, the Plan Administrator nor the Employer
     shall be required to see to the application of any such distribution so
     made to any of said persons, but said person's receipt shall be a full
     discharge of the Trustee's, the Plan Administrator's and the Employer's
     duties.

12.4 Qualified Domestic Relations Orders

     A.   Distributions

          In the event a person (hereafter called the "alternate payee") is
          designated by a qualified domestic relations order, as defined under
          Code Section 414(p), as having a right to receive all, or a portion
          of, the benefits payable under the Plan to a Participant, payment to
          the alternate payee may, to the extent provided by such order, begin
          at a time not permitted for distributions to the Participant. Payment
          to the alternate payee may be made as though the Participant had
          retired on the date on which the order requires payment to begin
          considering the present value

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page XII-4



          of benefits accrued by the Participant up to such date (but
          disregarding an Employer subsidy for early retirement). Payment may be
          made in any form permitted by the Plan other than in the form of a
          joint and survivor annuity with respect to the alternate payee and the
          alternate payee's spouse.

     B.   Separate Account Period

          If it is being determined whether a domestic relations order received
          in connection with a Participant is a qualified domestic relations
          order, the Plan Administrator shall separately account for the amounts
          that would have been paid to the alternate payee during the period of
          determination if the order was a qualified one. If the order is
          determined to be a qualified order at any time during the eighteen
          (18) month period beginning on the date on which the first payment
          would be required to be made under the qualified domestic relations
          order, the Plan Administrator shall pay the segregated amounts,
          including interest thereon, to the persons entitled to the amounts
          under the order. If it is determined that the order is not a qualified
          order or if at the end of the eighteen (18) month period it is still
          undetermined whether the order is a qualified order, the segregated
          amounts, including interest thereon, shall be paid to the persons who
          would have been entitled to the payments had there been no order. In
          the event it is determined that the order is a qualified order only
          after the eighteen (18) month period has elapsed, the application of
          the order shall be applied prospectively only, beginning as of such
          determination date.

     C.   Suspension of Benefits

          Notwithstanding any provision of the Plan to the contrary, in
          accordance with procedures established by the Plan Administrator, the
          Plan Administrator may temporarily suspend a Participant's right to
          borrow or withdraw from his Account or obtain a distribution from his
          Account, if (i) the Plan Administrator receives a domestic relations
          order and the Participant's Account is a source of the payment for
          such domestic relations order, or (ii) if the Plan Administrator
          receives notice that a domestic relations order is being sought by the
          Participant, his spouse, former spouse, child or other dependent (as
          defined in Code Section 152) and the Participant's Account is a source
          of the payment for such domestic relations order. Such suspension may
          continue for a reasonable period of time (as determined by the
          Administrator) which

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page XII-5



            may include the period of time the Plan Administrator, a court of
            competent jurisdiction or other appropriate person is determining
            whether the domestic relations order qualifies as a QDRO.

12.5   Hardship Distributions

       The Plan will allow hardship distributions. A distribution of all or a
       portion of the Participant's Elected Contributions Account (other than
       earnings credited thereto after December 31, 1988) and the Participant's
       Rollover Account may be made to a Participant upon the Participant's
       request if it is established that the Participant has an immediate and
       heavy financial need and the distribution is necessary to satisfy such
       need. The Plan Administrator shall establish the existence of the
       Participant's immediate and heavy financial need and the Participant's
       necessity for a distribution to satisfy such need by applying the
       following standards:

       A.   Immediate and Heavy Financial Need

            A need will be deemed to be an immediate and heavy financial need if
            it is to pay for one or more of the following:

            1.   Uninsured medical expenses described in Code Section 213(d)
                 incurred by the Participant, the Participant's Spouse, or any
                 dependent of the Participant (a dependent shall be determined
                 under Code Section 152) or necessary for such persons to
                 receive medical care, as defined in Code Section 213(d);

            2.   Purchase (excluding mortgage payments) of a principal residence
                 for the Participant;

            3.   Payment of tuition and related educational fees for the next 12
                 months of post-secondary education for the Participant or the
                 Participant's Spouse, children or dependents;

            4.   The need to prevent the eviction of the Participant from the
                 Participant's principal residence or foreclosure on the
                 mortgage of the Participant's principal residence; or

            5.   Any other reason recognized to constitute an immediate and
                 heavy financial need by the Commissioner of the Internal
                 Revenue Service in a revenue ruling, notice or other document
                 of general applicability. A need otherwise determined to
                 constitute

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            an immediate and heavy financial need will not fail to be such a
            need merely because the need is foreseeable or voluntarily incurred
            by the Participant.

B.     Distribution Necessary to Satisfy the Financial Need

       A distribution will be necessary to satisfy the immediate and heavy
       financial need only if all of the following requirements are satisfied:

       1.   The amount distributed does not exceed the amount of the heavy and
            immediate financial need, increased by any amounts necessary to pay
            any federal, state or local income taxes or penalties reasonably
            anticipated to result from the distribution;

       2.   The Participant has obtained all distributions (other than hardship
            distributions) and all nontaxable loans currently available to the
            Participant under the Plan and under all other qualified plans
            maintained by the Employer; and

       3.   The requirements of subsection C immediately below are satisfied.

C.     Restrictions

       The following restrictions will apply to a Member who receives a hardship
       withdrawal:

       1.   Upon receiving a distribution under this Section 12.5, the
            Participant's elective contributions (e.g., Participant Elected
            Contributions) and employee contributions under this Plan and all
            other plans maintained by the Employer or an Affiliate will be
            suspended for at least 12 consecutive months; and

       2.   A Participant who receives a distribution under this Section may not
            make elective contributions (e.g., Participant Elected
            Contributions) under the Plan or any other plans maintained by the
            Employer or an Affiliate for the Participant's taxable year
            (immediately following the taxable year of the hardship
            distribution) in excess of the Section 402(g) Limit for such taxable
            year less the amount of the Participant's elective contributions for
            the taxable year of the hardship distribution.

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       D.   Additional Rules

            The following rules shall apply to each request for a hardship
            distribution by a Participant.

            1.   The Participant's request for a hardship distribution shall be
                 made on such forms as are provided by the Plan Administrator
                 from time to time and the Participant shall furnish the Plan
                 Administrator with such information as the Plan Administrator
                 requests in its evaluation of the Participant's request;

            2.   The amount distributed, if any, shall in no event exceed the
                 balance of the Participant's Employee Deferral Contributions
                 Account (excluding earnings credited thereto after December 31,
                 1988) and Rollover Account; and

            3.   A Participant's request for a hardship distribution shall not
                 be honored to the extent it requires the distribution of an
                 amount serving as security for a loan to the Participant

12.6   Direct Rollover Distributions

       Notwithstanding any provision of the Plan to the contrary that would
       otherwise limit a distributee's election under this Section, a
       distributee may elect, at the time and in the manner prescribed by the
       Plan Administrator, to have any portion of an eligible rollover
       distribution paid directly to an eligible retirement plan specified by
       the distributee in a direct rollover.

       A.   Eligible Rollover Distribution

            An eligible rollover distribution is any distribution of all or any
            portion of the balance to the credit of the distributee, except that
            an eligible rollover distribution does not include: any distribution
            that is one of a series of substantially equal periodic payments
            (not less frequently than annually) made for the life (or life
            expectancy) of the distributee or the joint lives (or joint life
            expectancies) of the distributee and the distributee's designated
            beneficiary, or for a specified period of ten years or more; any
            distribution to the extent such a distribution is required under
            Code Section 401(a)(9); the portion of any distribution that is not
            includible in gross income (determined without regard to the
            exclusion for net unrealized appreciation with respect to employer
            securities); and any portion of a hardship withdrawal pursuant to
            Section 12.5 made

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page XII-8



            from a Participant's Employee Deferral Account after December 31,
            1998.

       B.   Eligible Retirement Plan

            An eligible retirement plan is an individual retirement account
            described in Code Section 408(a), an individual retirement annuity
            described in Code Section 408(b), an annuity plan described in Code
            Section 403(a), or a qualified trust described in Code Section
            401(a), that accepts the distributee's eligible rollover
            distribution. However, in the case of an eligible rollover
            distribution to the surviving spouse, an eligible retirement plan is
            an individual retirement account or individual retirement annuity.

       C.   Distributee

            A distributee includes an employee or former employee. In addition,
            the employee's or former employee's surviving spouse and the
            employee's or former employee's spouse or former spouse who is the
            alternate payee under a qualified domestic relations order, as
            defined in Code Section 414(p), are distributees with regard to the
            interest of the spouse or former spouse.

       D.   Direct Rollover

            A direct rollover is a payment by the Plan to the eligible
            retirement plan specified by the distributee.

12.7   Waiver of 30-Day Election Period

       If a distribution is one to which Code Sections 401(a)(11) and 417 do not
       apply, such distribution may commence less than 30 days after the notice
       required by Income Tax Regulation (S) Section 1.411(a)-11(c) is given
       provided (i) the Committee clearly informs the Participant that the
       Participant has a right to a period of at least 30 days after receiving
       the notice to consider the decision of whether or not to elect a
       distribution or a direct rollover, and (ii) the Participant, after
       receiving the notice, affirmatively elects a distribution or a direct
       rollover.

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page XII-9



                           XIII. TOP HEAVY PROVISIONS

13.1  Applicability

      Notwithstanding any other provision of the Plan to the contrary, the
      provisions of this Article shall apply for any Plan Year, beginning after
      December 31, 1983, in which the Plan is a Top-Heavy Plan as defined in
      Code Section 416(g).

13.2  Definitions

      A.   Aggregation Group

           Aggregation Group includes each plan maintained by the Employer or an
           Affiliate in which a Key Employee participates and each other plan
           maintained by the Employer or an Affiliate which enables any plan in
           which a Key Employee participates to meet the requirements of Code
           Section 401(a)(4) or 410. In addition, the Employer may elect to
           include other plans in the Aggregation Group which satisfy the
           requirements of Code Sections 401(a)(4) and 410 when considered
           together with the plans that are required to be aggregated. Any plan,
           however, that is or may be permissively included in the Aggregation
           Group upon an election by the Employer shall not be subject to the
           provisions of this Article.

      B.   Determination Date

           Determination Date shall be the last day of the preceding Plan Year
           or, if such Plan Year is the first Plan Year of the Plan, the last
           day of such Plan Year. In the case of plans included in an
           Aggregation Group, the present value of accrued benefits or accounts
           shall be combined for all aggregated plans that have a Determination
           Date that falls in the same calendar year.

      C.   Key Employee

           Key Employee means an Employee or a former Employee (or the
           beneficiary of such an Employee) who during the Plan Year ending on
           the Determination Date or during the four (4) preceding Plan Years
           is, as determined under Code Section 416(i):

Immunex Corporation Profit Sharing 401(k) Plan and Trust             Page XIII-1



      1.   An officer of the Employer having an annual compensation greater than
           50 percent of the amount in effect under Code Section 415(b)(1)(A);

      2.   One of the ten Employees having annual compensation from the Employer
           greater than the amount in effect under Code Section 415(c)(1)(A) and
           owning (or considered as owning within the meaning of Code Section
           318) the largest interest in the Employer;

      3.   A five (5) percent owner; or

      4.   A one (1) percent owner who has annual compensation from the Employer
           in excess of $150,000.

      Code Section 416(i) is hereby incorporated in the Plan by reference for
      the purpose of determining whether an Employee is a Key Employee, a former
      Key Employee, or a Non-Key Employee.

D.    Non-Key Employee

      Non-Key Employee means an Employee or a former Employee (or the
      beneficiary of such an Employee) who during the Plan Year ending on the
      Determination Date or during the four (4) preceding Plan Years is not a
      Key Employee or former Key Employee as defined under Code Section 416(i).

E.    Super Top-Heavy

      A plan or plans required to be included in the Aggregation Group shall be
      Super Top-Heavy for a Plan Year if on the Determination Date for such Plan
      Year the Top-Heavy Ratio exceeds ninety percent (90%).

F.    Top-Heavy

      A plan or plans required to be included in the Aggregation Group shall be
      Top-Heavy for a Plan Year if on the Determination Date for such Plan Year
      the Top-Heavy Ratio exceeds sixty percent (60%).

G.    Top-Heavy Ratio

      Top-Heavy Ratio means the ratio determined from dividing the present value
      of accrued benefits and accounts for Key Employees by the total

Immunex Corporation Profit Sharing 401(k) Plan and Trust             Page XIII-2



           value of accrued benefits and accounts for Key Employees and Non-Key
           Employees. The value of accrued benefits and accounts shall be
           determined as prescribed under paragraph H below.

     H.    Valuation of Accrued Benefit

           1.   Defined Contribution Plan

                The present value of an accrued benefit under a defined
                contribution plan is the account balance derived from Employer
                and nondeductible Employee contributions as of the most recent
                valuation date within the twelve (12) month period ending on the
                Determination Date, plus any contributions actually made since
                such date or, in the case of a plan subject to minimum funding
                requirements, contributions required to be made as of the
                Determination Date. All defined contribution plans required to
                be included or permissively included in the Aggregation Group
                shall be treated as a single plan.

           2.   Defined Benefit Plan

                The present value of an accrued benefit under a defined benefit
                plan is the value of the monthly retirement benefit derived from
                Employer or nondeductible Employee contributions, determined as
                of the most recent valuation date within the twelve (12) month
                period ending on the Determination Date, and determined as
                though the individual terminated service as of such valuation
                date. The benefit of Employee, other than a Key Employee, shall
                be treated as accruing under the method that is used for accrual
                purposes for all plans of the Employer and its Affiliates or, if
                there is no such method, as if such benefit accrued not more
                rapidly than the slowest accrual rate permitted under Code
                Section 411(b)(1)(C). Reasonable actuarial assumptions shall be
                used to determine the value of the benefit under the plan;
                provided, that assumptions as to future withdrawal or future
                salary increases shall not be used. All defined benefit plans
                required to be included or permissively included in the
                Aggregation Group shall be treated as a single plan and the same
                actuarial assumptions shall be used to value benefits under each
                of the plans included in the Aggregation Group.

Immunex Corporation Profit Sharing 401(k) Plan and Trust             Page XIII-3



           3.   Distributions Included

                In determining the present value of any accrued benefits and the
                amount of any account to be used to determine the Top-Heavy
                Ratio, distributions within the period of five (5) consecutive
                Plan Years ending on the Determination Date, and such rollover
                accounts as prescribed by regulation by the Secretary of the
                Treasury, shall be added to the value of accrued benefits as of
                such Determination Date. The accrued benefits of a former Key
                Employee and the accrued benefits of an individual who has not
                performed any services for the Employer maintaining the Plan at
                any time during the five (5) year period ending on the
                Determination Date shall, however, be disregarded.

13.3  Minimum Contributions

      For any Plan Year in which the Plan's Aggregation Group is Top-Heavy, the
      Employer contribution and forfeitures allocated to a Participant who is a
      Non-Key Employee in the employ of the Employer on the last day of the Plan
      Year shall be not less than the lesser of:

           A.   Three percent (3%) of the Participant's Compensation; or

           B.   The percentage at which contributions are made under the Plan
                for the Key Employee for whom such percentage is the highest for
                the Plan Year. In determining the contribution rate for a Key
                Employee, Employee elective contributions under a plan qualified
                under Code Section 401(k) shall be included.

                If the Plan is required to be included in an Aggregation Group
                and the Plan allows a defined benefit plan required to be in
                such Group to meet the requirements of Code Section 401(a)(4) or
                410, the minimum contribution, in such circumstances, shall be
                not less than three (3) percent of the Participant's
                Compensation for the Plan Year. All defined contribution plans
                required to be included in the Aggregation Group shall be
                treated as a single plan.

Immunex Corporation Profit Sharing 401(k) Plan and Trust             Page XIII-4



13.5  Benefits Under Different Plans

      If the Employer maintains one or more defined contribution plans (which
      shall be treated as a single defined contribution plan for purposes of
      this Article) in addition to a defined benefit plan and a Non-Key Employee
      participates in both types of plans, the Employer shall provide such
      Participant with the minimum benefit required under the defined benefit
      pension plan, offset, however, by any benefit provided under the
      Employer's defined contribution plan.

Immunex Corporation Profit Sharing 401(k) Plan and Trust             Page XIII-5



                       XIV. PROVISION AGAINST ANTICIPATION

Until distribution pursuant to the terms hereof, no Participant shall have the
right or power to alienate, anticipate, commute, pledge, encumber or assign any
of the benefits, proceeds or avails set aside for him under the terms of the
Plan, and no such benefits, proceeds or avails shall be subject to seizure by
any creditor of the Participant or the Employer under any writ or proceedings at
law or in equity, provided, that the terms of this Section shall not prohibit
the creation, assignment or recognition of a right to any benefit payable with
respect to a Participant if such creation, assignment or recognition of a right
is made under a qualified domestic relations order as defined under Code Section
414(p), a judgment, order, decree or settlement agreement described in Code
Section 401(a)(13) issued or entered into after August 4, 1997, or as security
for a loan from the Plan which is permitted pursuant to Code Section 4975.

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page XIV-1



XV.    ADMINISTRATIVE COMMITTEE - NAMED FIDUCIARY AND ADMINISTRATOR

15.1   Appointment of Committee

       The Employer shall appoint an Administrative Committee comprised of one
       or more persons (herein referred to as the Committee) to serve for such
       terms as the Employer may designate or until a successor has been
       appointed or until removal by the Employer. The Employer shall advise the
       Trustee in writing of the names of the members of the Committee and any
       changes thereafter made in the membership of the Committee. Vacancies due
       to resignation, death, removal or other causes shall be filled by the
       Employer. Members shall be bonded except as may otherwise be allowed by
       law. A member of the Committee may be paid reasonable compensation for
       the member's service, provided, that a member who is a full-time employee
       of the Employer shall serve without compensation. All reasonable expenses
       of the Committee shall be paid by the Employer. The number of the
       Committee may be changed by the Employer at any time.

15.2   Committee Action

       The Committee shall appoint a secretary who shall keep minutes of the
       Committee's proceedings and all data, records and documents pertaining to
       the Committee's administration of the Plan. The Committee shall act by
       majority vote of its members in office at that time, such vote to be
       taken at a meeting or, in writing, without a meeting. The Committee may,
       by such majority action, authorize its secretary or any one or more of
       its members to execute any document or documents on behalf of the
       Committee, in which event the Committee shall notify the Trustee in
       writing of such action and the name or names of those so designated. The
       Trustee shall accept and rely conclusively upon any direction or document
       executed by such secretary, member or members as representing action by
       the Committee until the Committee shall file with the Trustee a written
       revocation of such designation. A member of the Committee who is also a
       Participant hereunder shall not vote or act upon any matter relating
       solely to such member.

15.3   Rights and Duties

       The Committee shall be the Plan Administrator and Named Fiduciary of the
       Plan within the meaning of ERISA. The Committee, on behalf of the
       Participants and their Beneficiaries, shall have the authority to control
       and

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page XV-1



       manage the operation and administration of the Plan and shall have all
       powers and discretionary authority necessary to accomplish those
       purposes. It will interpret and apply all Plan provisions and may correct
       any defect, supply any omission or reconcile any inconsistency or
       ambiguity in such manner as it deems advisable. It will make all final
       determinations concerning eligibility, benefits and rights hereunder, and
       all other matters concerning plan administration and interpretation. All
       determinations and actions of the Committee will be conclusive and
       binding upon all persons, except as otherwise provided herein or by law,
       and except that the Committee may revoke or modify a determination or
       action previously made in error. Any action or omission by the Committee
       will be subject to review (by a court or otherwise) only for an abuse of
       discretion. The Committee will exercise all powers and authority given to
       it in a nondiscriminatory manner, and will apply uniform administrative
       rules of general application in order to assure similar treatment of
       persons in similar circumstances. The responsibility and authority of the
       Committee shall include, but shall not be limited to, the following:

       A.   Construing and interpreting the terms and provisions of the Plan;

       B.   Determining the eligibility of any person for benefits under the
            Plan, the amount of any such benefits and all other questions
            pertaining to the rights of Participants, their Spouses and their
            Beneficiaries hereunder;

       C.   Authorizing all disbursements by the Trustee from the Trust;

       D.   Maintaining all necessary records for the administration of the Plan
            other than those that the Trustee has specifically agreed to
            maintain;

       E.   Interpreting the provisions of the Plan and publishing such rules
            for the regulation of the Plan as are deemed necessary and not
            inconsistent with the terms of the Plan;

       F.   Establishing reasonable procedures to determine the qualified status
            of domestic relations orders and to administer distributions under
            such qualified orders;

       G.   Notifying the Participant and any other alternate payee, as defined
            under Code Section 414(p)(8), of the receipt of a domestic relations
            order, the Plan's procedures for determining the qualified status of
            such an order, and the determination made in connection with such
            order;

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page XV-2



       H.   Directing the Trustee to make distributions from the Trust Fund to
            Participants, former Participants, and beneficiaries of the Trust in
            accordance with the provisions of the Plan. The Trustee shall
            withhold from such distributions any amount required to be withheld
            pursuant to Code Section 3405 unless the recipient of such
            distributions has made an appropriate election under Code Section
            3405(a)(2) or 3405(b)(3).

15.4   Investments

       The Committee may appoint, in writing, an Investment Manager or Managers
       to manage and control all or part of the investments of the Plan. No
       appointment of an Investment Manager shall be effective until the
       Investment Manager has acknowledged in writing that the Investment
       Manager is a fiduciary of the Plan, and that the Investment Manager has
       complied with the bonding requirements of ERISA.

15.5   Information, Reporting and Disclosure

       To enable the Committee to perform its functions, the Employer shall
       supply full and timely information to the Committee on all matters
       relating to the Compensation of all Participants; their continuous,
       regular employment; their retirement, death or cause for termination of
       employment; and such other pertinent facts as the Committee may require,
       and the Committee shall furnish the Trustee such information as may be
       pertinent to the Trustee's administration of the Trust. The Committee, as
       Plan Administrator, shall have the responsibility of complying with the
       reporting and disclosure requirements of ERISA and, to the extent
       applicable, any other federal or state law.

15.6   Independent Qualified Accountant

       Unless the Plan is exempt from the requirement by applicable law or
       regulation, the Committee shall engage, on behalf of all Participants, an
       independent qualified public accountant who shall conduct such
       examinations of the financial statements of the Plan and of other books
       and records of the Plan as the accountant may deem necessary to enable
       the accountant to form an opinion as to whether the financial statements
       and schedules required by law to be included in any reports are presented
       fairly and in conformity with generally accepted accounting principles
       applied on a basis consistent with that of any preceding year.

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page XV-3



15.7   Standard of Care Imposed Upon the Committee

       The Committee shall discharge its duties with respect to the Plan solely
       in the interest of the Participants and Beneficiaries; and

       A.   For the exclusive purpose of providing benefits to Participants and
            their Beneficiaries and defraying reasonable expenses of the Plan;

       B.   With the care, skill, prudence and diligence under the circumstances
            then prevailing that a prudent person, acting in a like capacity and
            familiar with such matters, would use in the conduct of an
            enterprise of like character and with like aims; and

       C.   In accordance with the Plan provisions insofar as such provisions
            are consistent with the provisions of ERISA.

15.8   Allocation and Delegation of Responsibility

       The Committee may, by written rule promulgated under Section 15.3 above,
       allocate fiduciary responsibilities among Committee members and may
       delegate to persons other than Committee members the authority to carry
       out fiduciary responsibilities under the Plan, provided that no such
       responsibility shall be allocated or delegated to the Trustee without its
       written consent. As used in this part, the term "fiduciary
       responsibility" shall not include any responsibility provided in the
       Trust Agreement to manage or control the assets of the Plan.

       The Committee, in making the above allocation of fiduciary
       responsibilities, may provide that a person or group of persons may
       serve, with respect to the Plan, in more than one fiduciary capacity. The
       Committee or, so long as the Committee shall have made written approval,
       persons to whom fiduciary responsibilities have been delegated by the
       Committee may employ one or more persons to render advice with regard to
       any responsibility such fiduciary has under the Plan.

       In the event a fiduciary responsibility is allocated to a Committee
       member, no other Committee member shall be liable for any such act or
       omission of the person to whom the responsibility is allocated except as
       may be otherwise required by law. If a fiduciary responsibility is
       delegated to a person other than a Committee member, the Committee shall
       not be responsible or liable for an

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page XV-4



       act or omission of such person in carrying out such responsibility except
       as may otherwise be required by law.

15.9   Bonding

       Each fiduciary of the Plan and every person handling Plan funds shall be
       bonded unless exempt from such requirement by law. It shall be the
       obligation of the Committee to assure compliance with applicable bonding
       requirements. The Trustee shall not be responsible for assuring that
       bonding requirements are complied with and such responsibility is
       specifically allocated to the Committee.

15.10  Claims Procedure

       A.    Effective Date

             The claims procedure set forth below applies to claims decided on
             or after January 1, 2002. Claims decided prior to January 1, 2002,
             shall be decided under the claims procedure in effect at the time
             of such decision.

       B.    Filing Claim

             A Participant or a Beneficiary, or the authorized representative of
             either (the "Claimant"), who believes that he is then entitled to
             benefits hereunder may file a written claim for such benefits with
             the Secretary of the Administrative Committee. The Administrative
             Committee may prescribe a form for filing such claims, and, if it
             does so, a claim will not be deemed properly filed unless such form
             is used, but the Secretary of the Administrative Committee shall
             provide a copy of such form to any person whose claim for benefits
             is improper solely for this reason.

       C.    Claim Review

             Claims that are properly filed will be reviewed by the
             Administrative Committee, which will make its decision with respect
             to such claim and notify the Claimant in writing of such decision
             within 90 days (45 days in the case of a claim related to permanent
             disability (within the meaning of Section 11.2)) after the
             Secretary of the Administrative Committee's receipt of the written
             claim; provided that the 90-day period (45-day period in the case
             of a claim related to permanent disability (within the meaning of
             Section 11.2)) can be extended for up

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page XV-5



             to an additional 90 days (30 days in the case of a claim related to
             permanent disability (within the meaning of Section 11.2)) if the
             Administrative Committee determines that special circumstances
             require an extension of time to process the claim and the Claimant
             is notified of the extension, the reasons therefor, and the date by
             which the Administrative Committee expects to render a decision
             prior to the commencement of the extension. If the claim is wholly
             or partially denied, the written response to the Claimant shall
             include:

             1.   the specific reason or reasons for the adverse determination;

             2.   references to the specific provisions of the Plan document on
                  which the determination is based;

             3.   a description of any additional information necessary for the
                  Claimant to perfect his claim and an explanation why such
                  information is necessary;

             4.   a description of the Plan's review procedures (and the time
                  limits applicable thereto), as set forth in subsection (D)
                  immediately below;

             5.   a statement of the Claimant's right to bring a civil action
                  under ERISA Section 502(a) following an adverse benefit
                  determination on appeal; and

             6.   in the case of an adverse benefit determination related to
                  permanent disability (within the meaning of Section 11.2):

                  a.   if an internal rule, guideline, protocol or other similar
                       criterion was relied upon in making the adverse
                       determination, either the specific rule, guideline,
                       protocol or other similar criterion; or a statement that
                       such a rule, guideline, protocol or similar criterion was
                       relied upon in making the adverse determination and that
                       a copy of such rule, guideline, protocol or other
                       criterion will be provided free of charge to the Claimant
                       upon request; or

                  b.   if the adverse benefit determination is based on a
                       medical necessity or experimental treatment or similar
                       exclusion or limit, either an explanation of the
                       scientific or clinical judgment for the determination,
                       applying the terms of the

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page XV-6



                       Plan to the Claimant's medical circumstances, or a
                       statement that such explanation will be provided free of
                       charge upon request.

       D.    Appeal

             If the claim is denied in whole or in part, the Claimant may appeal
             such denial by filing a written request for appeal with the
             Secretary of the Administrative Committee within 60 days (180 days
             in the case of a claim related to permanent disability (within the
             meaning of Section 11.2)) of receiving written notice that the
             claim has been denied. Such written request for appeal should
             include:

             1.   a statement of the grounds on which the appeal is based;

             2.   reference to the specific provisions in the Plan document
                  which support the claim;

             3.   the reason or argument why the Claimant believes the claim
                  should be granted and evidence supporting each reason or
                  argument; and

             4.   any other relevant documents or comments that the Claimant
                  wishes to include.

             Appeals will be considered by the Administrative Committee, which
             will take into account all comments, documents, records and other
             information submitted by the Claimant relating to the claim,
             without regard to whether such information was submitted or
             considered in the initial determination. The Administrative
             Committee will make its decision with respect to any appeal, and
             notify the Claimant in writing of such decision, within 60 days (45
             days in the case of a claim related to permanent disability (within
             the meaning of Section 11.2)) after the Administrative Committee's
             receipt of the written request for appeal; provided that the 60-day
             period (45-day period in the case of a claim related to permanent
             disability (within the meaning of Section 11.2)) can be extended
             for up to an additional 60 days (45 days in the case of a claim
             related to permanent disability (within the meaning of Section
             11.2)) if the Administrative Committee determines that special
             circumstances require an extension of time to process the appeal
             and the Claimant is notified of the extension, and the reasons
             therefor, prior to

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page XV-7



             the commencement of the extension.  In the event the claim is
             denied on appeal, the written denial will include:

             1.   the specific reason or reasons for the adverse determination;

             2.   references to the specific provisions of the Plan document on
                  which the benefit determination is based;

             3.   a statement that the Claimant is entitled to receive, upon
                  request and free of charge, reasonable access to, and copies
                  of, documents, records, and other information relevant to the
                  Claimant's claim for benefits;

             4.   a statement of the Claimant's right to bring a civil action
                  under ERISA Section 502(a);

             5.   in the case of an adverse benefit determination related to
                  permanent disability (within the meaning of Section 11.2):

                  a.   if an internal rule, guideline, protocol or other similar
                       criterion was relied upon in making the adverse
                       determination, either the specific rule, guideline,
                       protocol or other similar criterion; or a statement that
                       such a rule, guideline, protocol or similar criterion was
                       relied upon in making the adverse determination and that
                       a copy of such rule, guideline, protocol or other
                       criterion will be provided free of charge to the Claimant
                       upon request;

                  b.   if the adverse benefit determination is based on a
                       medical necessity or experimental treatment or similar
                       exclusion or limit, either an explanation of the
                       scientific or clinical judgment for the determination,
                       applying the terms of the Plan to the Claimant's medical
                       circumstances, or a statement that such explanation will
                       be provided free of charge upon request; and

                  c.   the following statement: "You and your Plan may have
                       other voluntary alternative dispute resolution options,
                       such as mediation. One way to find out what may be
                       available is to contact your local U.S. Department of
                       Labor Office or your State insurance regulatory agency."

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page XV-8



       E.    Provision of Documents, Records and Other Information

             During the appeal period, the Claimant will be provided, upon
             request and free of charge, reasonable access to, and copies of,
             documents, records and other information relevant to his claim. A
             document, record or other information will be considered "relevant"
             to a Claimant's claim, if such document, record or other
             information:

             (1)  Was relied upon by the Administrative Committee in reaching
                  its decision on the claim;

             (2)  Was submitted, considered or generated in the course of
                  deciding the claim, without regard to whether the document,
                  record or other information was relied upon by the
                  Administrative Committee in reaching its decision on the
                  claim; or

             (3)  Demonstrates compliance with the administrative processes and
                  safeguards required under Department of Labor regulations in
                  making the benefit determination.

       F.    Standard of Review

             Any further review, judicial or otherwise, of the Administrative
             Committee's decision on the Claimant's claim will be limited to
             whether, in the particular instance, the Administrative Committee
             abused its discretion. In no event will such further review,
             judicial or otherwise, be on a de novo basis, as the Administrative
             Committee has discretionary authority to determine eligibility for
             benefits and to construe and interpret the terms of the Plan.

15.11  Unclaimed Account Procedures

       If a Participant or the Participant's Surviving Spouse or Beneficiary,
       if applicable, does not claim the Participant's vested Accrued Benefit,
       the Participant's vested Accrued Benefit shall be forfeited and applied
       in accordance with the provisions of Section 4.1B.3 or 5.2, as
       applicable. An unclaimed vested Accrued Benefit shall be forfeited on the
       later of the date that is 6 months after the date the Plan Administrator
       notifies the Participant, Surviving Spouse or Beneficiary, as applicable,
       by certified or registered mail addressed to his last known address, that
       he is entitled to a benefit or the date on which occurs the earlier of
       the Participant's attainment of Normal

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page XV-9



        Retirement Age or death, provided that the Participant, Surviving Spouse
        or Beneficiary has not made his whereabouts known prior to such date.

        If a Participant's vested Accrued Benefit is forfeited pursuant to this
        Section 15.11 and the Participant, Surviving Spouse or Beneficiary, as
        applicable, subsequently makes a claim for benefits, the forfeited
        Accrued Benefit shall be restored to the same dollar amount as was
        forfeited, unadjusted for any gains or losses occurring after the date
        on which it was forfeited. Such restoration shall be made first from the
        amount, if any, of Participant forfeitures occurring during the year of
        reinstatement. If such forfeitures are insufficient, restoration will be
        made from a special Employer contribution earmarked for that purpose.
        The reinstated vested Accrued Benefit shall be distribute to the
        Participant, Surviving Spouse or Beneficiary in accordance with the
        preceding provisions of the Plan.

15.12   Funding Policy

        The Committee shall be responsible for establishing and carrying out a
        funding policy for the Plan. In establishing such a policy, the
        short-term liquidity needs of the Plan shall be determined, to the
        extent possible, by considering, among other factors, the anticipated
        retirement date of Participants, turnover and contributions to be made
        by the Employer. In addition, all or a portion of the Plan's assets can
        be invested in "qualifying employer securities," within the meaning of
        Section 407(d)(5) of ERISA, including, but not limited to, common stock
        of Immunex Corporation. The funding policy and method so established
        shall be considered by the Committee in selecting Investment Funds
        pursuant to Section 6.1 and communicated by the Committee to any other
        fiduciary responsible for investment, including the Trustee and any
        Investment Manager, as applicable.

15.13   Indemnification

        The Employer does hereby indemnify and hold harmless each Committee
        member from any loss, claim or suit arising out of the performance of
        obligations imposed hereunder and not arising from said Committee
        member's willful neglect, misconduct or gross negligence.

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page XV-10



                     XVI. APPOINTMENT OF INVESTMENT MANAGER

16.1    Authority for Appointment

        The Plan Administrator shall have the authority prescribed in ERISA
        Section 402(c)(3) to appoint one or more Investment Managers and
        contract with each for management of any part of the Fund. Selection and
        retention of an Investment Manager shall be in the Plan Administrator's
        discretion. Each Investment Manager shall have the power to manage,
        acquire and dispose of that part of the Fund designated by the Plan
        Administrator. The Investment Manager has no responsibility for Plan
        operation or administration.

16.2    Investment Manager Discretion

        Without limitation of the foregoing and if an Investment Manager is
        appointed:

        A.   The Trustee, on Plan Administrator direction, shall segregate the
             Fund or any part thereof into one or more Investment Manager
             accounts. The Plan Administrator shall appoint an Investment
             Manager for each account and designate to the Trustee the part of
             the Fund to be managed by each Investment Manager. The Trustee
             shall send directly to the Investment Manager the proxies under the
             direction of the Investment Manager, who shall then vote such
             proxies at their discretion.

        B.   Upon request, the Plan Administrator shall advise others that the
             Investment Manager is authorized to enter orders for such
             Investment Manager's account, but the Trustee shall always have
             custody of account assets. The Trustee shall give the Investment
             Manager copies of, or extracts from, such portions of its records
             relating to such accounts as are necessary for the exercise of such
             Investment Manager's functions.

        C.   The Trustee shall neither question nor inquire about any action,
             direction or failure to give directions of any Investment Manager
             and shall not review the securities held in any Investment Manager
             account nor make any suggestions to the Investment Manager with
             respect to investment of, or disposition of, investments in any
             Investment Manager account. The Trustee shall not be liable for any
             act or omission of an Investment Manager or be under any obligation
             to invest or otherwise manage any asset of the Fund that is subject
             to the management of an Investment Manager. The Trustee shall not
             be liable for loss due to action or

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page XVI-1



             inaction complying with or in the absence of the Investment
             Manager's directions.

        D.   The Plan Administrator, by notice to the Trustee and the Investment
             Manager, may terminate at any time the authority of an Investment
             Manager to manage the account. In such event or upon resignation of
             an Investment Manager, the Plan Administrator shall either appoint
             a successor Investment Manager for the account or, with the
             Trustee's consent, direct the Trustee to assume responsibility for
             the investment management of the assets in the account, in which
             case such assets shall no longer be segregated from the other
             assets of the Fund. Until receipt of notice of such termination or
             resignation, the Trustee shall rely on the latest prior notice of
             the appointment of an Investment Manager.

        E.   Each Investment Manager to whom any fiduciary responsibility with
             respect to the Plan or Trust Fund is delegated shall discharge such
             responsibility in accordance with the standards set forth in ERISA
             Section 404(a).

        F.   Upon written direction of an Investment Manager received by the
             Trustee, the Trustee is authorized to purchase or sell stock,
             bonds, commercial paper, mortgages, or other securities or
             indebtedness of the Trustee or any of its affiliates.

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page XVI-2



                   XVII. INVESTMENT OF TRUST FUNDS BY TRUSTEE

The Trustee shall exercise authority or discretion in the management and control
of the assets of the Plan, except to the extent the selection of Investment
Funds for investment by Participants is made by the Committee and except to the
extent the management of any part of the Trust Fund has been delegated to any
Investment Manager pursuant to Article XVI. Without limiting the generality of
the foregoing, the Trustee shall invest and reinvest the principal and income of
the Trust Fund in common Investment Funds, real estate, real estate contracts,
government, municipal or corporation bonds, debentures or notes, including notes
secured by deeds of trust, common and preferred stocks, or other forms of
property whether real, personal or mixed, including investments for which
interest is guaranteed by a bank, insurance company or other financial
institution. In the event the Trustee invests any assets of the Plan in a common
Investment Fund maintained by the Trustee or any bank affiliated with the
Trustee (within the meaning of Section 1504 of the Code), the terms of such
common fund are hereby adopted as part of the Plan and such terms are, by this
reference, incorporated as part of this Document.

Immunex Corporation Profit Sharing 401(k) Plan and Trust             Page XVII-1



                       XVIII. POWERS AND DUTIES OF TRUSTEE

18.1    Powers of Trustee

        The Trustee shall have the following powers with regard to Trust assets.
        If investment discretion is exercised by a fiduciary or fiduciaries
        other than the Trustee, to the extent any of the following powers
        involve the exercise of investment discretion, the Trustee shall
        exercise such power at the direction of the investment fiduciary or
        fiduciaries.

        A.   To sell, convey, transfer, mortgage, pledge, lease or otherwise
             dispose of Trust assets without the approval of any court and
             without obligation upon any person dealing with the Trustee to see
             to the application of any money or other property delivered to it;

        B.   To exchange property or securities for other property or
             securities;

        C.   To keep any or all securities or other property in the name of a
             nominee, to deposit securities in a securities depository and hold
             them in the name of its nominee, and to hold securities in book
             entry form at a Federal Reserve Bank;

        D.   To vote, either in person or by proxy, any shares of stock or other
             securities held as part of the assets of the Trust, provided the
             Trustee shall forward proxies to the appropriate investment
             fiduciary, if the Trustee does not exercise investment discretion
             with respect to the security to be voted;

        E.   To collect, as the same shall become due and payable, the principal
             or income of the Trust and, if necessary, to take such legal
             proceedings as may deem advisable in the best interest of the Trust
             to collect any sum of money due the Trust. The Trustee shall be
             under no obligation to commence suit unless it shall have been
             first indemnified by the Trust Fund or the Employer with respect to
             expenses or losses to which it may be subjected through taking such
             action;

        F.   To borrow money for purposes of the Trust and to have power to
             execute and deliver notes, mortgages, pledges or other instruments
             as may be necessary in connection therewith;

Immunex Corporation Profit Sharing 401(k) Plan and Trust            Page XVIII-1



      G.   To pay the expenses of the Trust out of the Fund, including any taxes
           and reasonable compensation for its services as Trustee, if and to
           the extent that the Employer does not pay such expenses and
           compensation;

      H.   To receive and hold in safekeeping the assets of the Trust, provided
           assets invested in a registered mutual fund or in any similar pooled
           fund for which the Trustee is not the custodian shall be held in
           safekeeping by the custodian of such fund, and the Trustee shall not
           be responsible for their safekeeping;

      I.   To employ agents and to utilize the services of affiliates in
           performing its duties hereunder;

      J.   To deposit Trust funds in an interest-bearing account with a bank or
           similar financial institution, including the Trustee, provided such
           deposits shall bear a reasonable rate of interest;

      K.   To determine the fair market value of the Trust assets on an annual
           and other periodic basis. The Trustee shall perform such valuation in
           a reasonable and consistent manner in accordance with generally
           accepted accounting principles. The Trustee may utilize and shall be
           entitled to rely upon published quotation and pricing services that
           it considers reliable. In the event that the Committee or an
           Investment Manager directs investment into assets for which no
           published pricing information is available, the Trustee may obtain
           their fair market value from the Committee, the Investment Manager,
           or an appraiser selected by them, and shall be entitled to rely
           completely upon the value provided. If the Committee or Investment
           Manager is unable to unwilling to provide such valuation, the Trustee
           may engage an appraiser or other expert to determine the fair market
           value, and the fee for such service shall be an administrative
           expense of the Trust; and

      L.   Upon direction of the Committee or an Investment Manager,
           acquire and maintain deposit administration contracts,
           insurance company investment contracts, individual annuities,
           or group annuity policies ("Contracts"). The Trustee shall
           execute the application for a Contract and a Contract in such
           form as the investment fiduciary and the Trustee shall agree.
           The Trustee shall be the legal owner of all Contracts held in
           the Trust. Upon the direction of the investment fiduciary, the
           Trustee shall pay from the Trust the premiums, assessments,
           charges, or other costs to acquire and maintain Contracts. The
           Trustee shall have no duty

Immunex Corporation Profit Sharing 401(k) Plan and Trust            Page XVIII-2



           to make such payment unless the Trustee receives such direction. If
           the cash available in the Trust is not sufficient to pay all the sums
           the investment fiduciary has directed the Trustee to pay, the Trustee
           shall promptly notify the investment fiduciary of the deficiency, and
           the Trustee shall have no duty to make any such payment until it
           receives sufficient cash to make the payment. Upon direction of the
           investment fiduciary, the Trustee shall collect and receive dividends
           or other income of the Contract or leave the income with the issuing
           company; convert from one form of Contract to another; designate a
           mode of settlement of the proceeds of a Contract; sell or assign a
           Contract; surrender a Contract for cash; agree with the issuing
           company to any release, modification, reduction, or amendment
           thereof; and without limitation exercise any other right, option, or
           privilege that belongs to the legal owner of a Contract. The Trustee
           shall have no discretion with respect to the exercise of any of the
           foregoing powers or any other action permitted by a Contract held in
           the Trust, but it shall exercise such powers or take such action only
           upon the direction of the investment fiduciary.

      M.   Generally, with relation to the assets of the Trust, to do all such
           acts, execute all such instruments, take all such proceedings and
           exercise all such rights and privileges as it deems necessary to
           carry out its obligations hereunder to the extent consistent with the
           rights of Participants and Beneficiaries and the standard of care
           imposed by Section 18.4;

18.2  Annual Accounts

      The Trustee, within a reasonable period following the close of each Plan
      Year (not to exceed 120 days), shall render to the Plan Administrator a
      certified account of its administration of the Trust during the preceding
      year, which shall include such information maintained by the Trustee
      necessary to enable the Plan Administrator to comply with the reporting
      requirements of federal law. The Plan Administrator shall promptly review
      the Trustee's accountings and shall file any exceptions within 120 days of
      receipt. In the event it files no exception within such 120-day period,
      the accounting shall be deemed settled for the period covered by it.

Immunex Corporation Profit Sharing 401(k) Plan and Trust            Page XVIII-3



18.3  Notices and Directions

      Whenever a notice or direction is given to the Trustee, the instrument
      shall be signed by a person or persons duly authorized by resolution,
      minutes, or similar action to act on behalf of the Employer, the Plan
      Administrator, an Investment Manager, or any other person or agent with
      authority to direct the Trustee ("Authorized Person"). The Trustee shall
      be protected in acting upon any such notice, resolution, order,
      certificate, opinion, telegram, letter or other document believed to be
      genuine and to have been signed by the proper party or parties, and may
      act thereon without notice to any Participant and without considering the
      rights of any Participant.

      An Authorized Person may give, and the Trustee may rely upon, facsimile
      instructions. An Authorized Person is responsible to verify that facsimile
      instructions delivered to the Trustee are legible in form, clear in
      content, and properly executed. The Trustee shall not be liable for the
      security measures followed by an Authorized Person with respect to
      transmission of facsimile instructions. Should any person request
      disbursement by wire, the Trustee may require as a condition to such
      disbursement that such person conform to Trustee's standard policies and
      procedures for funds transfer and execute Trustee's standard funds
      transfer agreement.

      The Trustee shall not be required to determine or make any investigation
      to determine' the identity or mailing address of any person entitled to
      benefits under the Plan and shall send checks and other papers to such
      persons at addresses as may be furnished it by the Plan Administrator.

18.4  Standard of Care Imposed Upon Trustee

      The Trustee shall discharge its responsibilities under the Plan and Trust
      solely in the interests of the Participants and Beneficiaries; and

      A.   For the exclusive purpose of providing benefits to Participants and
           their Beneficiaries and defraying reasonable expenses of
           administering the Plan;

      B.   With care, skill, prudence and diligence under the circumstances then
           prevailing that a prudent person, acting in a like capacity and
           familiar with such matters, would use in the conduct of an enterprise
           of a like character and with like aims;

Immunex Corporation Profit Sharing 401(k) Plan and Trust            Page XVIII-4



      C.   To the extent it exercises investment discretion, by diversifying the
           investments of the Plan so as to minimize the risk of large losses,
           unless under the circumstances it is clearly prudent not to do so;
           and

      D.   In accordance with the terms of this Plan and Trust Agreement insofar
           as such provisions are consistent with the provisions of ERISA.

18.5  Trustee's Acknowledgment of Responsibility

      The Trustee appointed under the Plan and Trust shall acknowledge and
      accept its appointment by signing this Document or by signing a separate
      document of acceptance which incorporates the Plan and Trust by reference.
      The Trustee's acknowledgment or acceptance of any modification of this
      Document shall be necessary if such modification changes the duties of the
      Trustee in any way.

Immunex Corporation Profit Sharing 401(k) Plan and Trust            Page XVIII-5



                                XIX. CONSTRUCTION

This Agreement shall be construed in accordance with the Code, ERISA and
regulations issued thereunder and, to the extent not superseded thereby, the
laws of the State of Washington.

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page XIX-1



                            XX. LIABILITY OF TRUSTEE

20.1   Actions of Trustee Conclusive

       In the performance of its duties under the Trust, the Trustee shall
       exercise good faith and comply with the standard of care imposed upon it
       and with the terms of this Agreement. The Trustee shall have the
       authority to interpret its responsibilities hereunder, and, in the
       absence of fraud or breach of fiduciary responsibility, the Trustee's
       interpretation shall be conclusive. In case any dispute or doubt arises
       as to the Trustee's rights, liabilities or duties hereunder, the Trustee
       may employ counsel and take the advice of such counsel as it may select
       and shall be fully protected in acting upon and following such advice,
       except to the extent otherwise provided by law. The Trustee shall be
       entitled to reimburse itself from the Trust Fund for reasonable expenses
       thereby incurred, to the extent such expenses are not paid by the
       Employer.

20.2   Distributions by Trustee

       Until the Trustee receives written notice of any agreement or occurrence
       having effect upon any rights hereunder, including but not limited to
       birth, marriage, divorce, death and/or agreements between Spouses, the
       Trustee shall incur no liability for distributions made.

20.3   Expenses of Administration

       In the event the Employer files for reorganization or protection from
       creditors under the bankruptcy laws, or files a petition in bankruptcy,
       or an assignment of assets for creditors, the Trustee shall pay from
       Trust assets any unpaid expenses for services rendered to the Plan,
       including but not limited to administration, actuarial and consulting
       services.

20.4   Indemnity of Trustee

       The Employer shall indemnify and hold harmless the Trustee from any loss
       or liability (including reasonable attorneys' fees) incurred as a result
       of (a) following any direction (or not acting in the absence of
       direction) from the Employer, the Plan Administrator, an Investment
       Manager, or any other person authorized by the Employer to issue
       direction to the Trustee; and (b) its good faith performance of its
       duties hereunder, except for its own negligence, breach of fiduciary
       duty, or willful misconduct.

Immunex Corporation Profit Sharing 401(k) Plan and Trust               Page XX-1



                     XXI. RESIGNATION OR REMOVAL OF TRUSTEE

21.1   Resignation

       The Trustee may resign at any time by giving the Employer at least sixty
       (60) days written notice of such resignation sent by registered mail. In
       such event, the Employer shall designate a successor Trustee within sixty
       (60) days, and failing in which, the Trustee may petition an appropriate
       court to designate a successor Trustee, which successor Trustee may be a
       corporate Trustee or an individual Trustee.

21.2   Removal

       The Employer may remove a Trustee with or without cause by giving the
       Trustee at least sixty (60) days' written notice and by appointing a
       successor Trustee, Trustees, corporate or individual, or any combination
       of Trustees.

21.3   Settlement of Account

       Upon the resignation or removal of the Trustee, all right, title and
       interest of such Trustee in the assets of the Trust and all rights and
       privileges under this Agreement theretofore vested in such Trustee, shall
       vest in the successor Trustee, and thereupon, all future liability of
       such Trustee shall terminate; provided, however, that the Trustee shall
       execute, acknowledge and deliver all documents and written instruments
       which are necessary to transfer and convey the right, title and interest
       in the Trust assets and all rights and privileges to the successor
       Trustee.

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page XXI-1



                                   XXII. SUITS

If any person or party to this Agreement shall request the Trustee to bring any
action at law or suit in equity to determine any of the provisions or rights
arising out of this Agreement, the Trustee shall not be obligated to bring such
suit unless the Trustee is fully indemnified for all costs of such action,
including a reasonable sum for attorneys' fees.

Immunex Corporation Profit Sharing 401(k) Plan and Trust             Page XXII-1



                        XXIII. MERGERS AND CONSOLIDATIONS

In the case of any merger or consolidation with any other plan or a transfer of
assets or liabilities to any other plan, each Participant shall be entitled to
be credited with a benefit immediately after such merger, consolidation or
transfer which is equal to the benefit to which he would have been entitled
immediately before such merger or consolidation had the Plan then terminated.

Immunex Corporation Profit Sharing 401(k) Plan and Trust            Page XXIII-1



                     XXIV AMENDMENT AND TERMINATION OF PLAN

24.1   Right to Amend and Terminate

       The Employer represents that the Plan is intended to be a continuing and
       permanent program for Participants but reserves the right to terminate
       the Plan at any time. The Employer may modify, alter or amend the Plan in
       whole or in part, at any time and for any reason.

24.2   No Revesting

       No termination, modification, alteration or amendment shall have the
       effect of revesting in the Employer any of its contributions or the
       income derived therefrom.

24.3   Exclusive Benefit of Participants

       At no time during the existence hereof or at its termination may the Plan
       assets be used for or directed to purposes other than for the exclusive
       benefit of Participants or their Beneficiaries.

24.4   Termination and Discontinuance of Contributions

       The Employer shall have the right, at any time, to discontinue its
       contributions hereunder and to terminate, or partially terminate, this
       Agreement (and the Plan and Trust established hereunder). Upon complete
       discontinuance of the Employer's contributions or full or partial
       termination of the Plan, the Accounts and rights to benefits of all
       affected Participants shall become fully vested and shall not thereafter
       be subject to forfeiture, except to the extent that law or regulations
       may preclude such vesting in order to prevent discrimination in favor of
       Highly Compensated Employees. Upon final termination of the Plan, the
       Plan Administrator shall direct the Trustee to distribute to the
       Participants all assets remaining in the Trust after payment of any
       expenses properly chargeable against the Trust in accordance with the
       value credited to such Participants, as of the date of such termination,
       in cash or in kind and in such manner as the Plan Administrator shall
       determine.

Immunex Corporation Profit Sharing 401(k) Plan and Trust             Page XXIV-1



                        XXV. RIGHT TO DISCHARGE EMPLOYEES

Neither the establishment of the Plan, nor any modification thereof, nor the
payment of any benefit shall be construed as giving any Participant or any other
person any legal or equitable right against the Employer or the Trustee, unless
the same shall be specifically provided for in the Plan, nor as giving any
Employee or Participant the right to be retained in the employ of the Employer.
All Employees shall remain subject to discharge by the Employer to the same
extent as if the Plan had never been adopted.

Immunex Corporation Profit Sharing 401(k) Plan and Trust              Page XXV-1



                          XXVI. RETURN OF CONTRIBUTIONS

26.1  Mistake of Fact

      In the event a contribution is made by reason of a mistake of fact, the
      amount that would not have been contributed had the mistake not occurred
      may be returned to the Employer if the amount is returned within one year
      of the mistaken contribution.

26.2  Allowance of Deductibility

      All contributions to the Plan are conditioned upon their deductibility
      under Code Section 404. Notwithstanding any provision herein to the
      contrary, to the extent a deduction is disallowed, the deduction shall be
      returned to the Employer if the Employer so requests and the amount is
      returned within one year of the disallowance.

Immunex Corporation Profit Sharing 401(k) Plan and Trust             Page XXVI-1



                               XXVII. PUERTO RICO

To the extent Puerto Rican law imposes different limits or requirements than
those set forth above for plan qualification, the terms and provisions of the
Plan shall be deemed to have been modified to reflect those limits and
requirements with respect to any Eligible Employees employed in Puerto Rico.

Immunex Corporation Profit Sharing 401(k) Plan and Trust            Page XXVII-2



      IN WITNESS WHEREOF, the parties hereto have caused this Document to be
executed this 25th day of February, 2002.

                                            IMMUNEX CORPORATION

                                            By: /s/ David A. Mann
                                                --------------------------------
                                               Title Executive Vice President
                                                     ---------------------------
                                                     and Chief Financial Officer
                                                     ---------------------------

                                            SECURITY TRUST COMPANY, as Trustee

                                            By: /s/ Nicole McDermott
                                                --------------------------------
                                               Title Vice President
                                                     ---------------------------

Immunex Corporation Profit Sharing 401(k) Plan and Trust            Page XXVII-3



                                 AMENDMENT NO. 1
                                       TO
                               IMMUNEX CORPORATION
                      PROFIT SHARING 401(k) PLAN AND TRUST

     This Amendment No. 1 is made to the Immunex Corporation Profit Sharing
401(k) Plan and Trust (the "Plan"), which was originally effective January 1,
1987, and most recently amended and restated effective January 1, 2000. All
terms defined in the Plan shall have the same meaning when used herein. All
provisions of the Plan not amended by this Amendment No. 1 shall remain in full
force and effect.

     Effective March 1, 2002, the first sentence of Section 4.1A is amended to
read as follows:

          Each Participant may elect, effective as of the first day of any
     month coincident with or following the Participant's Enrollment Date, by
     filing a Salary Deferral Agreement with the Plan Administrator within
     such time as the Plan Administrator may determine, to defer any whole
     percentage of the Participant's Compensation not to exceed 30%, but in
     any event, the amount of deferral shall not exceed the Section 402(g)
     Limit.

     The Employer has caused this Amendment to be executed on the date indicated
below.

                                              IMMUNEX CORPORATION


Dated: February 28, 2002                      By: /s/ Philip Laub
                                                 -------------------------------
                                                 Its: VP, HR
                                                     ---------------------------



                                 AMENDMENT NO. 2
                                       TO
                               IMMUNEX CORPORATION
                      PROFIT SHARING 401(K) PLAN AND TRUST

     This Amendment No. 2 is made to the Immunex Corporation Profit Sharing
401(k) Plan and Trust (the "Plan"), which was originally effective January 1,
1987, and most recently amended and restated effective January 1, 2000. All
terms defined in the Plan shall have the same meaning when used herein. This
Amendment shall be effective as of the effective date of Amgen Inc.'s
acquisition of Immunex Corporation. All provisions of the Plan not amended by
this Amendment No. 2 shall remain in full force and effect.

     1.  The name of the Plan is hereby changed to the Amgen Inc. Profit Sharing
401(k) Plan and Trust, and all references in the Plan thereto are hereby revised
accordingly. To that end, Section 1.1 is amended to read as follows:

         1.1  Name

              This Plan shall be known as the Amgen Inc. Profit Sharing 401(k)
              Plan and Trust.

     2.  Section 2.6 is amended to read as follows:

         2.6  Board

              "Board" means the Board of Directors of Amgen Inc.

     3.  Sections 2.6 (Code) through 2.35 (Year of Service) are renumbered as
Sections 2.7 through 2.36, respectively, and all references thereto in the Plan
are revised accordingly.

     4.  Effective March 1, 2002, the third sentence of the first paragraph of
Section 2.8 (as renumbered) is amended to read as follows:

         Notwithstanding the foregoing, (i) Compensation shall include
         amounts excludable from the Employee's gross income by reason of
         Code Section 125, 402(e)(3), 402(h) or 403(b), and (ii) solely
         for purposes of Sections 2.27, 4.1A, 4.1E, 4.2A and 5.2A,
         Compensation shall not include commissions or, effective March 1,
         2002, any amounts paid pursuant to the Immunex Corporation
         Retention Plan or the Immunex Corporation Employee Severance
         Plan.

     5.  Section 2.11 (as renumbered) is amended to read as follows:

         2.11 Employer



          "Employer" means Immunex Corporation (or any successor thereof) and
          any Affiliate that, with the consent of the Board, elects to adopt the
          Plan; provided, that for purposes of Article XV (Administrative
          Committee), Article XXI (Resignation or Removal of Trustee) and
          Article XXIV (Amendment and Termination of Plan), Employer means Amgen
          Inc.

6.   Sections 6.4, 6.5 and 6.6 are amended to read as follows:

     6.4  Voting of Stock Held in Investment Funds

          With respect to each Participant's investment in any Investment Fund,
          other than the Amgen Inc. Common Stock Fund, the Trustee shall vote
          the number of shares credited to each Participant's Account, in each
          case, in a manner that the Trustee believes to be consistent with its
          fiduciary duties under Section 404 of ERISA.

     6.5  Voting of Amgen Stock

          With respect to each Participant's investment in the Amgen Inc. Common
          Stock Fund, before each annual or special meeting of the stockholders
          of Amgen Inc., Amgen Inc. will furnish such Participant with a copy of
          the proxy solicitation material for such meeting, together with a form
          addressed to the Trustee requesting the Participant's confidential
          instructions on how the shares of Amgen Inc. common stock ("Shares")
          allocated to the Participant's Account should be voted on each matter
          to come before the meeting. The number of Shares allocated to a
          Participant's Account will be determined by multiplying the number of
          Shares held in the Amgen Inc. Common Stock Fund as of the applicable
          record date by a fraction, the numerator of which is the number of
          units of such Fund held in the Participant's Account as of the
          applicable record date and the denominator of which is the total
          number of outstanding units of such Fund as of such date. Upon receipt
          of such instructions, the Trustee shall vote Shares allocated to each
          Participant's Account (including fractional as well as whole Shares)
          in accordance with timely directions of such Participant; provided,
          that a failure of a Participant to timely and affirmatively direct the
          manner in which Shares allocated to the Participant's Account are to
          be voted shall be deemed for purposes of this Section to be an
          affirmative direction to abstain from voting.

     6.6  Tender of Amgen Stock

          The Trustee shall, with respect to Shares allocated to that portion of
          each Participant's Account invested in the Amgen Inc. Common Stock

                                     Page 2



               Fund, act in response to any tender offer or exchange offer for
               Shares commenced by a person or persons, including, but not
               limited to, a tender offer or exchange offer within the meaning
               of the Securities Exchange Act of 1934, as amended from time to
               time (all such tender or exchange offers collectively, a "tender
               offer"), in accordance with timely directions of such
               Participant; provided, that a failure of a Participant to timely
               and affirmatively direct the manner in which the Trustee is to
               act in response to a tender offer with respect to Shares
               allocated to the Participant's Account shall be deemed for
               purposes of this Section to be an affirmative direction not to
               take action with respect to such Shares. For purposes of
               determining the number of Shares to be the subject of any
               particular response to a tender offer, the Trustee shall use the
               nearest practicable date as determined by the Trustee. The number
               of Shares allocated to a Participant's Account will be determined
               by multiplying the number of Shares held in the Amgen Inc. Common
               Stock Fund as of the relevant date by a fraction, the numerator
               of which is the number of units of such Fund held in the
               Participant's Account as of such date and the denominator of
               which is the total number of outstanding units of such Fund as of
               such date. Amgen Inc. and the Trustee each shall use its best
               efforts to timely distribute or to cause to be distributed to
               each Participant such information as is being distributed to
               other stockholders of Amgen Inc. in connection with any such
               tender offer.

     7.   The last sentence of Section 12.1(A) is amended to read as follows:

          Notwithstanding the foregoing, if the Plan Administrator establishes
          an Investment Fund that is designed to invest primarily in the common
          stock of Amgen Inc., a Participant (or Beneficiary, as applicable) may
          elect to receive such whole shares of Amgen Inc. common stock as are
          allocated to that portion of the Participant's vested Accounts that is
          invested in such Investment Fund (with cash for any fractional
          shares), in lieu of receiving cash for such portion of the
          Participant's Accounts.

     8.   The third sentence of Section 15.12 is amended to read as follows:

          In addition, all or a portion of the Plan's assets can be invested in
          "qualifying employer securities," within the meaning of Section
          407(d)(5) of ERISA, including, but not limited to, common stock of
          Amgen Inc.

     The Employer has caused this Amendment No. 2 to be executed on the date
indicated below.

                               IMMUNEX CORPORATION

                                     Page 3



Dated:   July 12, 2002                      By:   /s/ Edward Fritzky
       -------------------------                --------------------------------
                                                  Its:  Chief Executive Officer
                                                       -------------------------

Accepted:

                                            SECURITY TRUST COMPANY, as Trustee

                                            By:  /s/ Nicole McDermott
                                                --------------------------------
Dated:   July 15, 2002                            Its:  Vice President
       -------------------------                       -------------------------

                                     Page 4

                                                                    EXHIBIT 23.1

               CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS

         We consent to the incorporation by reference in the Registration
Statement (Form S-8) of Amgen Inc. pertaining to the Amgen Inc. Amended and
Restated 1993 Equity Incentive Plan (formerly known as the Immunex Corporation
1993 Stock Option Plan), Amgen Inc. Amended and Restated 1999 Equity Incentive
Plan (formerly known as the Immunex Corporation 1999 Stock Option Plan), Amgen
Inc. Amended and Restated 1999 Employee Stock Purchase Plan (formerly known as
the Immunex Corporation 1999 Employee Stock Purchase Plan), Immunex Corporation
Stock Option Plan for Nonemployee Directors and Amgen Inc. Profit Sharing 401(k)
Plan and Trust (formerly known as the Immunex Corporation Profit Sharing 401(k)
Plan and Trust) of our report dated January 22, 2002, with respect to the
consolidated financial statements and schedule of Amgen Inc., included in its
Annual Report (Form 10-K) for the year ended December 31, 2001, filed with the
Securities and Exchange Commission.


Los Angeles, California                                /s/ ERNST & YOUNG LLP
July 16, 2002

                                                                    Exhibit 23.2

               CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS

     We consent to the incorporation by reference in the Registration Statement
(Form S-8) of Amgen Inc. for the registration of shares of its common stock of
our report dated January 22, 2002 (except for Note 16, as to which the date is
March 8, 2002), with respect to the consolidated financial statements of Immunex
Corporation included in the Current Report (Form 8-K) dated May 16, 2002 of
Amgen Inc., filed with the Securities and Exchange Commission.

                                                           /s/ ERNST & YOUNG LLP

Seattle, Washington
July 16, 2002