- --------------------------------------------------------------------------------
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                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                 ---------------

                                 SCHEDULE 14D-1
               TENDER OFFER STATEMENT PURSUANT TO SECTION 14(d)(1)
                     OF THE SECURITIES EXCHANGE ACT OF 1934

                                 AMENDMENT NO. 1

                                   AMGEN INC.
                            (Name of Subject Company)

                              PHARMAINVEST, L.L.C.
                        PHARMACEUTICAL ROYALTIES, L.L.C.
                     PHARMACEUTICAL ROYALTY INVESTMENTS LTD.
                        PHARMACEUTICAL PARTNERS, L.L.C.
                                    (Bidders)

       CONTRACTUAL CONTINGENT PAYMENT RIGHTS ARISING FROM THE PURCHASE OF
                                CLASS A INTERESTS
                        OF AMGEN CLINICAL PARTNERS, L.P.
                         (Title of Class of Securities)

                                      NONE
                      (CUSIP Number of Class of Securities)

                                 ---------------

                          PABLO LEGORRETA, DAVE MADDEN
                              PHARMAINVEST, L.L.C.
                           70 E. 55th St., 23rd Floor
                               New York, NY 10022
                                 (800) 600-1450

                                 ---------------

                                   COPIES TO:
                             F. GEORGE DAVITT, ESQ.
                         TESTA, HURWITZ & THIBEAULT, LLP
                       HIGH STREET TOWER  125 HIGH STREET
                                BOSTON, MA 02110
                      (Name, Address and Telephone Number
           of Person Authorized to Receive Notices and Communications
                              on Behalf of Bidder)

                                 ---------------

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This Amendment No. 1 amends and supplements the Tender Offer Statement on 
Schedule 14D-1 filed by PharmaInvest, L.L.C., a Delaware limited liability 
company (the "Purchaser"), on behalf of Pharmaceutical Royalties, L.L.C., a 
Delaware limited liability company, and Pharmaceutical Royalty Investments 
Ltd., a Bermuda company (collectively the "Funds"), and on behalf of 
Pharmaceutical Partners, L.L.C., a Delaware limited liability company and the 
sole member of the Purchaser, relating to the offer by Purchaser to purchase 
outstanding contractual contingent payment rights arising from the purchase 
of Class A Interests of Amgen Clinical Partners, L.P. (the "CCPRs") at 
$240,000 per CCPR, net to the seller in cash, without interest thereon, on 
the terms and subject to the conditions set forth in the Offer to Purchase, 
dated August 21, 1997 (the "Offer to Purchase"), and in the related Letter of 
Transmittal and any amendments or supplements thereto, copies of which are 
attached hereto as Exhibits (a)(1) and (a)(2), respectively (which 
collectively constitute the "Offer"). Those sections of the Offer amended and 
supplemented by the Supplement dated September 18, 1997 are hereby 
incorporated by reference in the Items of the Schedule in which such sections 
are referred to.

     As of 5:00 p.m. New York City time, on Wednesday, September 17, 1997, 
  approximately 33 CCPRs had been tendered in the Offer.
    

     The Expiration Date of the Offer is hereby amended so that the Offer 
  will expire at 12:00 midnight, New York City time on September 24, 1997.

   
ITEM 11. MATERIAL TO FILED AS EXHIBITS

     Item 11 is hereby amended as follows:
    
     (a)(4) Supplement to the Offer to Purchase dated September 18, 1997.

     (a)(5) Cover Letter from PharmaInvest, L.L.C. dated September 18, 1997.

     (a)(6) Press Release dated September 18, 1997.

                                        2



                                   SIGNATURES

    After due inquiry and to the best of my knowledge and belief, I certify
that the information set forth in this statement is true, complete and correct.

Dated: September 18, 1997             PHARMAINVEST, L.L.C.

                                      By:    /s/ Pablo Legorreta
                                         -------------------------------------
                                      Name:  Pablo Legorreta

                                      Title:  Managing Member of Pharmaceutical
                                              Partners, L.L.C., the Manager
                                            -----------------------------------


                                      PHARMACEUTICAL ROYALTIES, L.L.C.

                                      By:    /s/ Pablo Legorreta
                                         --------------------------------------
                                      Name:  Pablo Legorreta

                                      Title: Managing Member of Pharmaceutical
                                             Partners, L.L.C., the Manager
                                            -----------------------------------


                                      PHARMACEUTICAL ROYALTY
                                      INVESTMENTS LTD.

                                      By:    /s/ Pablo Legorreta
                                         --------------------------------------
                                      Name:  Pablo Legorreta

                                      Title: Managing Member of Pharmaceutical
                                             Partners, L.L.C., the Manager
                                            -----------------------------------

                                      PHARMACEUTICAL PARTNERS, L.L.C.

                                      By:   /s/ Pablo Legurreta
                                          -------------------------------------
                                      Name: Pablo Legorreta

                                      Title: Managing Member
                                             ----------------------------------


                                        3



                                  EXHIBIT INDEX

   
  EXHIBIT                          DESCRIPTION
  ------        -------------------------------------------------------
99.4(a)(4)    Supplement to the Offer to Purchase dated September 18, 1997
99.5(a)(5)    Cover Letter from PharmaInvest, L.L.C. dated September 18, 1997
99.6(a)(6)    Press Release dated September 18, 1997
    
                                       4





                                                               EXHIBIT (a)(4)

                                    SUPPLEMENT TO
                              OFFER TO PURCHASE FOR CASH
             UP TO 160 OUTSTANDING CONTRACTUAL CONTINGENT PAYMENT RIGHTS
                                    (THE "CCPRs")
                  ARISING FROM THE PURCHASE OF CLASS A INTERESTS OF
                            AMGEN CLINICAL PARTNERS, L.P.
                                          AT
                                $240,000 NET PER CCPR
                                          BY
                                 PHARMAINVEST, L.L.C.
                                           
               The following information amends and supplements the Offer to 
Purchase dated August 21, 1997 by PharmaInvest, L.L.C., a Delaware limited 
liability company (the "Purchaser"), on behalf of Pharmaceutical Royalties, 
L.L.C., a Delaware limited liability company, and Pharmaceutical Royalty 
Investments Ltd., a Bermuda company (collectively, the "Funds"), and on 
behalf of Pharmaceutical Partners, L.L.C., a Delaware limited liability 
Company, of up to 160 outstanding contractual contingent payment rights 
arising from the purchase of Class A Interests of Amgen Clinical Partners, 
L.P. (the "CCPRs"), for cash consideration per CCPR of $240,000 (the 
"Purchase Price") upon the terms and subject to the conditions set forth in 
the Offer to Purchase, this Supplement, and the related Letter of Transmittal 
(which, together with any amendments or supplements hereto or thereto, 
collectively constitute the "Offer").  Except as set forth in this Supplement 
the terms and conditions previously set forth in the Offer to Purchase and 
Letter of Transmittal remain applicable in all respects to the Offer.  
Capitalized terms used but not defined in this Supplement have the meanings 
assigned in the Offer to Purchase.

               According to the most recent quarterly letter dated May 30, 
1997, there are 838 CCPRs issued and outstanding.  The Offer is subject to 
proration.  See Section 2 of the Offer.  

               The Expiration Date of the Offer is hereby amended so that the 
Offer will expire at 12:00 midnight, New York City time on September 24, 1997.

               The Offer is conditioned upon, among other things, the 
agreement of Amgen to transfer CCPRs to the Purchaser, a condition which in 
the reasonable discretion of the Purchaser must be satisfied or waived prior 
to the Expiration Date, and the satisfaction of the Purchaser prior to the 
Expiration Date that upon the purchase of the CCPRs pursuant to the Offer, 
the Purchaser, the Funds and/or their nominee, in the Purchaser's reasonable 
discretion, will have full rights to ownership of the CCPRs and will become 
assignees of the purchased CCPRs.  The Offer is also subject to certain other 
conditions contained in the Offer.  See Sections 2 and 14 of the Offer.

               See the Risk Factors on page 2 of this Supplement.  




RISK FACTORS


               Before tendering, Holders are urged to consider the following 
risk factors in addition to the information previously provided:

               -    Although the Purchaser cannot predict the future value of 
                    the CCPRs, the Purchase Price could differ significantly 
                    from the proceeds that would be realized by holding the 
                    CCPRs for the entire life of the expected payment stream.

               -    The Purchaser is making the Offer with a view to making a 
                    profit. Accordingly, there may be a conflict between the 
                    desire of the Purchaser to acquire the CCPRs at the 
                    Purchase Price and the ultimate value of the CCPRs at the 
                    end of the applicable payment stream.  There can be no 
                    assurance that the Purchase Price will exceed or fall 
                    below such ultimate value.  

               -    No independent person has been retained by the Purchaser 
                    or any of its affiliates to value or make any appraisal 
                    of the CCPRs or to render any opinion with respect to the 
                    fairness of the Purchase Price and no representation is 
                    made with respect to the fairness of the Purchase Price.

               -    The Purchaser believes that there is a limited market for 
                    resale of the CCPRs.  While the Offer represents an 
                    opportunity for any holder of CCPRs to obtain liquidity, 
                    there can be no assurance that in the future a market 
                    will not develop or that another party will not make an 
                    offer for the CCPRs.  The Purchaser has no reason to 
                    believe that any such market will develop.  The Purchaser 
                    has no current plans itself to make another tender offer 
                    for the CCPRs.


               The CCPRs represent the right to receive cash payments derived 
from the revenue of Neupogen, a product developed and marketed by Amgen Inc. 
as an adjunct to chemotherapy.  In determining the Purchase Price, the 
Purchaser considered a number of factors including its own estimates, on the 
basis of publicly available information, of the potential future cash 
payments that may be produced by the CCPRs throughout the remaining eight 
year life of the payments, the risks inherent in the future cash flows, the 
nature of the CCPRs, the CCPRs' exclusive dependence on the sales of a single 
product and the absence of any market for the CCPRs.  The Purchaser is 
assuming the risk that its estimate of the potential future cash payments 
will be realized.  No third party was retained to value the CCPRs or to 
render any fairness opinion with respect to the Purchase Price.  No 
representation is made as to the fairness of the Purchase Price.  No other 
valuation analysis was performed or used, including any liquidation value or 
net asset value analysis.  In determining the Purchase Price, the Purchaser 
considered the absence of a secondary market for CCPRs. Affiliates of the 
Purchaser have previously purchased CCPRs (see Section 6 of the Offer) at 
prices per CCPR equal to or less than the Purchase Price; however, in 
determining the Purchase Price, the Purchaser did not consider the prices 
paid by affiliates of the Purchaser for such other purchases of CCPRs or the 
price paid for CCPRs by any third party.  The Purchaser is not aware of any 
other tender offer having been made for the CCPRs.

               The Introduction of the Offer to Purchase is hereby amended by 
inserting the following paragraph in place of the current fifth paragraph:

INTRODUCTION

               The Offer is conditioned upon, among other things, Purchaser 
being satisfied prior to the Expiration Date, in its reasonable discretion, 
that upon purchase of the CCPRs pursuant to the

                                       2



Offer it, the Funds and/or their nominee will have full rights to ownership as
to all such CCPRs and that it, the Funds, and/or their nominee will become the
registered holder of the purchased CCPRs.  The Offer is also subject to certain
other conditions contained in this Offer to Purchase.  See Section 2 and 14.

               Section 2 of the Offer to Purchase is hereby amended by 
inserting the following paragraphs in place of the current second and third 
paragraph:

2. PRORATION; ACCEPTANCE FOR PAYMENT AND PAYMENT

               In the event that proration is required, the Purchaser will 
promptly announce the final results of such proration after the Expiration 
Date.

               Upon the terms and subject to the conditions of the Offer 
(including, if the Offer is extended or amended, the terms and conditions of 
any such extension or amendment), Purchaser will accept for payment (and 
thereby purchase) and pay for all CCPRs which are validly tendered (and not 
properly withdrawn) prior to the Expiration Date, promptly following the 
Expiration Date.  Subject to the applicable rules of the Commission, 
including Rule 14e-1(c), Purchaser expressly reserves the right to delay 
acceptance for payment of or payment for CCPRs pending receipt of any 
regulatory approval specified in Section 15 or in order to comply, in whole 
or in part, with any other applicable law or government regulation.  See 
Sections 14 and 15.

               Section 3 of the Offer to Purchase is amended by restating the 
following paragraphs:

3.  PROCEDURE FOR TENDERING FOR CCPRs.

               DETERMINATION OF VALIDITY.  All questions as to the form of 
documents and the validity, eligibility (including time of receipt) and 
acceptance for payment of any tender of CCPRs pursuant to any of the 
procedures described above will be determined by Purchaser in its reasonable 
discretion, which determination shall be final and binding on all parties.  
Purchaser reserves the absolute right to reject any or all tenders of CCPRs 
determined not to be in proper form or the acceptance of or payment for which 
may, in the opinion of counsel, be unlawful and reserves the absolute right 
to waive any defect or irregularity in any tender of CCPRs.  Purchaser also 
reserves the absolute right to waive or amend any or all of the conditions of 
the Offer prior to the Expiration Date. Purchaser's interpretation of the 
terms and conditions of the Offer (including the Letter of Transmittal and 
its instructions) will be final and binding on all parties.  No tender of 
CCPRs will be deemed to have been validly made, until all defects and 
irregularities have been cured or waived.  None of Purchaser, the Depositary, 
the Information Agent or any other person will be under any duty to give 
notification of any defects or irregularities in tenders or incur any 
liability for failure to give any such notification.

               APPOINTMENT as PROXY.  By executing and delivering the Letter 
of Transmittal, a tendering Holder irrevocably appoints designees of 
Purchaser as his or her attorneys-in-fact and proxies, with full power of 
substitution, in the manner set forth in the Letter of Transmittal, to the 
full extent of the Holder's rights with respect to the CCPRs (and with 
respect to any and all other securities issued or issuable in respect of such 
CCPRs on or after the date hereof) tendered by the Holder.  All such powers 
of attorney and proxies will be considered coupled with an interest in the 
tendered CCPRs and all prior powers of attorney and proxies given by the 
Holder with respect to the CCPRs will be revoked, without further action, and 
no subsequent powers of attorney and proxies may be given (and, if given, 
will not be deemed effective) by the Holder.  

                                       3



Designees of Purchaser will be empowered to exercise all voting and other 
rights of the Holder with respect to such CCPRs as they in their reasonable 
discretion may deem proper, including, without limitation, in respect of any 
annual or special meeting of the Holders, or any adjournment or postponement 
of any such meeting, or in connection with any action by written consent in 
lieu of any such meeting or otherwise.  Purchaser reserves the absolute right 
to require that, in order for CCPRs to be validly tendered, immediately upon 
Purchaser's acceptance for payment of the CCPRs, Purchaser must be able to 
exercise full voting and other rights with respect to the Units.

               Section 4 of the Offer to Purchase is hereby amended by 
inserting the following paragraph in place of the third paragraph:

4. WITHDRAWAL RIGHTS

               For a withdrawal to be effective, a written, telegraphic or 
facsimile transmission notice of withdrawal must be timely received by the 
Depositary at its address set forth on the back cover or the Offer to 
Purchase.  Any such notice of withdrawal must specify the name of the persons 
who tendered the CCPRs to be withdrawn, the number of Units to be withdrawn 
and the name of the registered Holder, if different from that of the person 
who tendered the CCPRs. All questions as to the form and validity (including 
time of receipt) of notices of withdrawal will be determined by Purchaser, in 
its reasonable discretion, whose determination will be final and binding on 
all parties.  No withdrawal of CCPRs will be deemed to have been made 
properly until all defects and irregularities have been cured or waived.  
None of Purchaser, the Depositary, the Information Agent or any other person 
will be under any duty to give notification of any defects or irregularities 
in any notice of withdrawal or incur any liability for failing to give such 
notification.

               Section 14 of the Offer to Purchase is hereby amended by 
inserting the following paragraphs in place of the first, fifth and last 
paragraphs:

14.  CERTAIN CONDITIONS OF THE OFFER

               Notwithstanding any other provision of the Offer, Purchaser 
shall not be required to accept for payment or, subject to any application 
rules and regulations of the Commission, including Rule 14e-1(c) under the 
Exchange Act (relating to Purchaser's obligation to pay for or return 
tendered CCPRs promptly after expiration or termination of the Offer), to pay 
for any CCPRs tendered, and may postpone the acceptance for payment or, 
subject to the restriction referred to above, payment for any CCPRs tendered, 
and may amend or terminate the Offer if, (i) Purchaser is not satisfied prior 
to the Expiration Date, in its reasonable discretion, that, upon purchase of 
the CCPRs pursuant to the Offer, it, the Funds  and/or their nominee will 
have full rights to ownership as to all such CCPRs and that it, the Funds 
and/or their nominee will become registered holders of CCPRs, (ii) all 
material regulatory and related approvals have not been obtained or made on 
terms reasonably satisfactory to Purchaser prior to the Expiration Date, or 
(iii) at any time prior to the Expiration Date any of the following events 
shall occur or shall be deemed by Purchaser to have occurred:

               (D)  any change (or any development involving a prospective 
change shall have occurred or be threatened in the business, financial 
condition, results of operations, or prospects of Amgen's Neupogen franchise 
which, in the reasonable discretion of the Purchaser, is, or may be, 
materially adverse to the Holders, or the Purchaser shall become aware of any 
fact (including 

                                       4



without limitation any such change or development) which, in the reasonable 
discretion of the Purchaser, has, or may have, materially adverse 
significance with respect to the Holders; 

               The foregoing conditions are for the sole benefit of Purchaser 
and its affiliates and may be asserted by Purchaser regardless of the 
circumstances (other than any action or inaction by Purchaser or any of their 
affiliates) giving rise to any such condition or may be waived by Purchaser, 
in whole or in part, from time to time prior to the Expiration Date in its 
reasonable discretion.  The failure by Purchaser at any time to exercise any 
of the foregoing rights shall not be deemed a waiver of any such right and 
each such right shall be deemed an ongoing right and may be asserted at any 
time and from time to time.  Any reasonable determination by Purchaser 
concerning any of the events described herein shall be final and binding.


September 18, 1997                                     PHARMAINVEST, L.L.C.
                                           PHARMACEUTICAL ROYALTIES, L.L.C.
                                    PHARMACEUTICAL ROYALTY INVESTMENTS LTD.
                                            PHARMACEUTICAL PARTNERS, L.L.C.


                                       5




                                                           EXHIBIT (a)(5)

                                                       September 18, 1997


To Holders of Amgen CCPRs:

Accompanying this letter is an amendment to the Offer to purchase Amgen CCPRs 
made by PharmaInvest, L.L.C. on August 21, 1997.  This amendment reflects 
changes in the disclosure document previously sent to you, but does not 
change the $240,000 per CCPR purchase price.  As a result of the amendment, 
we are extending the offer to midnight (New York City time) on 
September 24, 1997.

Thank you for taking the time to consider the Offer.

Very truly yours,

PharmaInvest, L.L.C.




                                                             EXHIBIT (a)(6)

                      PHARMAINVEST, L.L.C. EXTENDS TENDER OFFER
                                           
    NEW YORK, NEW YORK, (September 18, 1997).........PharmaInvest, L.L.C., 
has announced that its offer to purchase outstanding contractual contingent 
payment rights ("CCPRs") arising from the Purchase of Class A Interests of 
Amgen Clinical Partners, L.P. for $240,000 per CCPR has been extended and is 
now scheduled to expire at 12:00 Midnight, (Eastern Standard Time), on 
September 24, 1997.  As of 5:00 p.m. on September 17, 1997, approximately 
33 CCPRs had been tendered and not withdrawn.

    For additional information, contact The Herman Group, Inc., the 
Information Agent/Depository for the Offer at (800) 354-0049.