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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. 3)
 
                                 SYNERGEN, INC.
                           (NAME OF SUBJECT COMPANY)
 
                       AMGEN ACQUISITION SUBSIDIARY, INC.
 
                                   AMGEN INC.
                                    (BIDDER)
 
                          COMMON STOCK, $.01 PAR VALUE
                         (TITLE OF CLASS OF SECURITIES)
 
                                   871594107
                      (CUSIP NUMBER OF CLASS OF SECURITIES)
 
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                         MARGARET VALEUR-JENSEN, PH.D.
                                 SENIOR COUNSEL
                                   AMGEN INC.
                                  AMGEN CENTER
                             1840 DEHAVILLAND DRIVE
                          THOUSAND OAKS, CA 91320-1789
                           TELEPHONE: (805) 447-1000
                     (NAME, ADDRESS AND TELEPHONE NUMBER OF
                     PERSONS AUTHORIZED TO RECEIVE NOTICES
                    AND COMMUNICATIONS ON BEHALF OF BIDDER)
 
                            ------------------------
 
                                    COPY TO:
 
                            GEORGE A. VANDEMAN, ESQ.
                                LATHAM & WATKINS
                       633 WEST FIFTH STREET, SUITE 4000
                         LOS ANGELES, CALIFORNIA 90071
                           TELEPHONE: (213) 485-1234
 
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                                  TENDER OFFER
 
     Amgen Acquisition Subsidiary, Inc., a Delaware corporation ("Purchaser")
and Amgen Inc., a Delaware corporation ("Parent") hereby amend and supplement
their Tender Offer Statement on Schedule 14D-1 (the "Statement") originally
filed on November 23, 1994, as amended by Amendment No. 1 filed on December 2,
1994 and Amendment No. 2 filed on December 14, 1994, with respect to Purchaser's
offer to purchase all outstanding shares of Common Stock, par value $.01 per
share, of Synergen, Inc., a Delaware corporation (the "Company"), including the
associated preferred stock purchase rights at a price of $9.25 per share, net to
the seller in cash, upon the terms and subject to the conditions set forth in
Purchaser's Offer to Purchase dated November 23, 1994 and in the related Letter
of Transmittal.
 
ITEM 10. ADDITIONAL INFORMATION.
 
     (e) On December 9, 1994, the Company filed an answer in the case captioned
Anna Stanley and Len Kahn v. Larry Soll, et al., Case No. 13892 (Del. Ch. Nov.
18, 1994). A copy of the answer is attached hereto as Exhibit 99.(9)(15) and is
incorporated herein by this reference.
 
     On December 15, 1994 and pursuant to the Memorandum of Understanding
entered into on November 17, 1994, the parties to the litigation captioned In re
Synergen, Inc. Securities Litigation, Case No. 93-B-402 (the "Class Action"),
entered into a Stipulation of Settlement (the "Stipulation") settling, subject
to certain conditions, the Class Action. The Stipulation was filed with the
United States District Court for the District of Colorado (the "Court") on
December 15 and the Court issued an Order on that day preliminarily approving
the Stipulation. Assuming that the conditions to the Stipulation are satisfied
and the Stipulation is finally approved by the Court, the Company and its
insurers will contribute $28 million in exchange for a full release of all
claims asserted in or related to the Class Action. The execution of the
Stipulation settling the Class Action is a condition to the completion of
Purchaser's tender offer, and assuming that the Stipulation remains in full
force and effect, the condition will be satisfied.
 
ITEM 11. MATERIAL TO BE FILED AS EXHIBITS.
 
     99.(a)(15) Answer filed in litigation captioned Anna Stanley and Ken Kahn
                v. Larry Soll, et al., Case No. 13892 (Del. Ch. November 18,
                1994).
 
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                                   SIGNATURE
 
     After due inquiry and to the best of the undersigned's knowledge and
belief, the undersigned certifies that the information set forth in this
statement is true, correct and complete.
 
                                          AMGEN ACQUISITION SUBSIDIARY, INC.
 
                                          By   /s/  Thomas E. Workman, Jr.
                                             -------------------------------
                                                  Chief Executive Officer
 
Dated: December 19, 1994
 
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                                   SIGNATURE
 
     After due inquiry and to the best of the undersigned's knowledge and
belief, the undersigned certifies that the information set forth in this
statement is true, correct and complete.
 
                                          AMGEN INC.
 
                                          By     /s/  Gordon M. Binder
                                              -------------------------------
                                                Chief Executive Officer and
                                                   Chairman of the Board
 
Dated: December 19, 1994
 
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                                 EXHIBIT INDEX
 
SEQUENTIALLY EXHIBIT NUMBERED NUMBER DESCRIPTION PAGE - ----------- ----------- ------------ 99.(a)(15) Answer filed in litigation captioned Anna Stanley and Ken Kahn v. Larry Soll, et al., Case No. 13892 (Del. Ch. November 18, 1994).......
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               IN THE COURT OF CHANCERY OF THE STATE OF DELAWARE
                          IN AND FOR NEW CASTLE COUNTY
 
                                C. A. No. 13892
 
                           ANNA STANLEY and KEN KAHN,
                                  Plaintiffs,
 
                                       v.
 
               LARRY SOLL, GREGORY B. ABBOTT, ROBERT C. THOMPSON,
        ARTHUR H. HAYES, DAVID I. HIRSH, BARRY MACTAGGART, GLENN S. UTT,
                    ROBERT F. HENDRICKSON and SYNERGEN INC.,
                                  Defendants.
 
                               DEFENDANTS' ANSWER
 
     1. This paragraph (i) describes plaintiffs, pleading technique, as to which
no responsive pleading is required, and (ii) characterizes the Synergen Offer,
which offer speaks for itself.
 
     2. Denied.
 
     3. Denied.
 
     4. The factual allegations are denied. The remainder of the paragraph
states a legal conclusion, as to which no responsive pleading is required.
 
                                    PARTIES
 
     5. Plaintiffs are not registered stockholders reflected on the transfer
records of Synergen, Inc. Defendants are therefore without sufficient knowledge
to admit or deny the allegation and, on that basis, it is denied.
 
     6. Admitted.
 
     7. The first sentence is admitted. The second sentence is denied.
 
     8. The first sentence is admitted. The second sentence is denied.
 
     9. Admitted that Robert C. Thompson is the Executive Vice President,
Research and Clinical Affairs, and a director. The balance of the paragraph is
denied.
 
     10. Admitted.
 
     11. This paragraph describes plaintiffs' pleading technique, as to which no
responsive pleading is required.
 
     12. This paragraph states a legal conclusion, as to which no responsive
pleading is required.
 
     13. Defendants deny engaging in any unlawful acts, plans, schemes, or
transactions as complained of by plaintiffs. The remainder of this paragraph
alleges plaintiffs' pleading technique, and legal conclusions, as to which no
responsive pleading is required.
 
                            CLASS ACTION ALLEGATIONS
 
     14. This paragraph describes plaintiffs' pleading technique, as to which no
responsive pleading is required.
 
     15. Denied.
 
     16. The first sentence states a legal conclusion, as to which no responsive
pleading is required. The second sentence is admitted.
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     17. Denied.
 
     18. As to the first sentence, (i) defendants are without knowledge as to
plaintiffs' prosecutorial commitment and (ii) are not required to respond to
plaintiffs' evaluation of the competence and experience of their attorneys. As
to the balance of this paragraph, defendants are without sufficient knowledge to
admit or deny, and it therefore is denied.
 
     19. This paragraph alleges legal conclusions, as to which no responsive
pleading is required.
 
     20. Denied.
 
                            SUBSTANTIVE ALLEGATIONS
 
     21. Denied.
 
     22. The November 18, 1994, Dow Jones News Wire speaks for itself. The
remainder of the paragraph characterizes the merger agreement, which agreement
speaks for itself.
 
     23. Denied.
 
     24. The first sentence is admitted. As to the second sentence, Synergen
denies that its reported revenues were $3,636,100 for the second quarter of
1993, but admits the remainder of the sentence.
 
                             CERTIFICATE OF SERVICE
 
     I, William D. Johnston, Esquire hereby certify that, on December 9, 1994,
two copies of the foregoing document were served by hand upon the following
attorney of record:
 
                                          Norman M. Monhait, Esquire
                                          Rosenthal, Monhait, Gross & Goddess
                                          First Federal Plaza
                                          P.O. Box 1070
                                          Wilmington, DE 19899
 
                                                   WILLIAM D. JOHNSTON
                                          -------------------------------------
                                                   William D. Johnston
 
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