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                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13D

                    Under the Securities Exchange Act of 1934
                               (Amendment No. 1 )*

                       LIGAND PHARMACEUTICALS INCORPORATED
                                (Name of Issuer)

                          COMMON STOCK, $.001 PAR VALUE
                         (Title of Class of Securities)

                                    53220K207
                                 (CUSIP Number)

      JAMES B. LOOTENS, ASSISTANT SECRETARY AND ASSOCIATE GENERAL COUNSEL,
                 ELI LILLY AND COMPANY, LILLY CORPORATE CENTER,
                    INDIANAPOLIS, INDIANA 46285 317-276-5835
                  (Name, Address and Telephone Number of Person
                Authorized to Receive Notices and Communications)

                                  MAY 11, 1998
                      (Date of Event which Requires Filing
                               of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition which is the subject of this Schedule 13D, and is filing this
schedule because of Rule 13d-1(e), 13d-1(f), or 13d-1(g), check the following
box [  ].

    Note: Schedules filed in paper format shall include a signed original and
    five copies of the schedule, including all exhibits. See Rule 13d-7(b) for
    other parties to whom copies are to be sent.

    *The remainder of this cover page shall be filled out for a reporting
    person's initial filing on this form with respect to the subject class of
    securities, and for any subsequent amendment containing information which
    would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).

(Continued on following pages)

                                      Page 1







                                                   

CUSIP No.                                                 53220K207

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

(1)     Names of Reporting Persons:                       Eli Lilly and Company
        S.S. or I.R.S. Identification                     35-0470950
        Nos. of Above Persons

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

(2)     Check the Appropriate Box                         (a) _________________
        if a Member of a Group                            (b) _________________
                                                          Not Applicable

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

(3)     SEC Use Only

- --------------------------------------------------------------------------------
(4)     Source of Funds                                   Not Applicable

- --------------------------------------------------------------------------------
(5)     Check if Disclosure of Legal
        Proceedings is Required Pursuant
        to Items 2(d) or 2(e)                             Not Applicable

- --------------------------------------------------------------------------------
(6)     Citizenship or Place of Organization              Indiana

- --------------------------------------------------------------------------------
Number of Shares             (7)   Sole Voting            2,176,279
  Beneficially Owned               Power
  by Each Reporting          (8)   Shared Voting          None
  Person With                      Power
                             (9)   Sole Dispositive       2,176,279
                                   Power
                             (10)  Shared Disposi-        None
                                   tive Power

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

(11)   Aggregate Amount Beneficially                      2,176,279
       Owned by Each Reporting Person
- --------------------------------------------------------------------------------

(12)   Check if the Aggregate Amount                      Not Applicable
       In Row (11) Excludes Certain Shares

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

(13)   Percent of Class Represented                       5.6%
       by Amount in Row (11)
- --------------------------------------------------------------------------------

(14)   Type of Reporting Person                           CO

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


                                     Page 2







Item 4. Purpose of Transaction

        On May 11, 1998, the Issuer, a wholly-owned merger subsidiary of the
Issuer, and Seragen, Inc. ("Seragen") entered into an Agreement and Plan of
Reorganization under which it is proposed that Seragen become a wholly-owned
subsidiary of the Issuer. Pursuant to this proposed merger (the "Merger"),
Seragen common stock will be converted into a right to receive, among other
things, common stock of the Issuer. Specifically, at the closing of the Merger
Seragen shareholders will receive 0.035746 shares of Issuer common stock for
each share of Seragen common stock (the "Closing Consideration"). Further,
additional consideration (the "Milestone Consideration") of $0.23 per share of
common stock of Seragen will be paid by the Issuer six months following FDA
approval of Seragen's investigational product DAB389IL-2 in the United States
for cutaneous T-cell lymphoma if such approval is supported to any material
extent by clinical and development efforts of Seragen prior to the consummation
of the merger. The Milestone Consideration will, however, only be payable by the
Issuer if the required FDA approval is obtained within two years of the Merger
Closing. The Issuer may in its discretion pay the Milestone Consideration in the
form of cash or the Issuer's common stock or a combination thereof. Any stock
delivered as part of the Milestone Consideration will be valued on a trailing
average market price for the ten trading days prior to issuance.

        Eli Lilly and Company ("Lilly") currently holds 1,787,092 shares of
Seragen common stock. Accordingly, Lilly would receive approximately 63,881
shares of the Issuer's common stock in connection with the Closing
Consideration.

        In addition, on May 11, 1998, Lilly and the Issuer entered into a Third
Amendment to Option and Wholesale Purchase Agreement ("Third Amendment"). The
original Option and Wholesale Purchase Agreement was filed as Exhibit B to the
original Schedule 13D filed by Lilly on December 5, 1997. The Third Amendment
amends and restates Section 1.3 of the Option and Wholesale Purchase Agreement.
The primary effect of the Third Amendment is to modify the timing during which,
at the Issuer's election, Lilly may become obligated to purchase $20,000,000 of
the Issuer's common stock. The Third Amendment is filed herewith as Exhibit B
and is incorporated by reference herein.

Item 6. Contracts, Arrangements, Understandings or Relationships With
Securities of the Issuer.

        A copy of the Third Amendment to Option Agreement, as described in
response to Item 4 above is filed herewith as Exhibit A and is incorporated
herein by reference.


                                     Page 3






        Also on May 11, 1998, Lilly and the Issuer entered into a letter
agreement (the "Lockup Agreement") under which Lilly agreed that any shares of
Issuer common stock it may receive pursuant to the Merger will be subject to the
transfer restrictions set forth in Section 4.1 of the Stock Purchase Agreement
dated November 25, 1997 between Lilly and the Issuer (a copy of which was filed
as Exhibit A to the original Schedule 13D filed by Lilly on December 5, 1997).
The Lockup Agreement is filed herewith as Exhibit B and is incorporated by
reference herein.

Item 7. Material to be Filed as Exhibits.

               Exhibit A.    Third Amendment to Option and Wholesale Purchase 
                             Agreement dated as of May 11, 1998, between Lilly 
                             and the Issuer

               Exhibit B.    Letter Agreement dated May 11, 1998, between
                             Lilly and the Issuer.

                                    SIGNATURE

        After reasonable 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.

                                            ELI LILLY AND COMPANY

                                            /s/ Edwin W. Miller
                                            ------------------------
                                            Edwin W. Miller
                                            Vice President and Treasurer

Date:  May 21, 1998

                                     Page 4








                  AMENDMENT NO. 3 TO OPTION AND WHOLESALE PURCHASE AGREEMENT

        This Amendment is executed as of the 11th day of May, 1998 by and
between Eli Lilly and Company ("Lilly") and Ligand Pharmaceuticals Incorporated
("Ligand").

        WHEREAS, Lilly and Ligand have entered into an Option and Wholesale
Purchase Agreement dated as of November 25, 1997, amended on February 23, 1998
and further amended on March 16, 1998 (the "Agreement"); and

        WHEREAS, the parties now desire to amend the Agreement to limit the time
period during which Section 1.3 of the Agreement will be operative.

        NOW, therefore, in consideration of the foregoing, the mutual covenants
set forth below and other consideration, receipt and sufficiency of which are
hereby acknowledged, the parties agree as follows:

        1.      Section 1.3 of the Agreement is hereby amended to read in its 
entirety as follows:

        "1.3 CASH/ROYALTY OPTION. On or before the earlier of (i) January 31,
        1999 or (ii) the Effective Date (as defined therein) of the Agreement
        between Ligand and Lilly dated May 11, 1998 (the "Subsequent Agreement")
        (collectively, (i) and (ii) shall be known as the "Cash/Royalty
        Termination Date"), Ligand may determine to exercise the Cash/Royalty
        Option (as defined below), by delivery of written notice to Lilly
        informing Lilly of its decision to exercise the Cash/Royalty Option (the
        "Cash/Royalty Notice"). Upon delivery of the Cash/Royalty Notice, this
        Agreement shall automatically terminate and the parties only surviving
        rights and obligations under this Agreement shall be as follows
        (collectively, (a) and (b) below shall be known as the `Cash/Royalty
        Option"):

               (a) Subject to the terms and conditions set forth in the stock
        purchase agreement described in Section 4.6, Lilly shall purchase from
        Ligand, and Ligand shall sell and issue to Lilly, for Twenty Million
        Dollars ($20,000,000), the number of shares of Ligand's voting common
        stock (the "Shares") equal to Twenty Million Dollars ($20,000,000)
        divided by one hundred twenty percent (120%) of the average daily
        closing price for the Shares as reported by the National Association of
        Securities Dealers, Inc. on the twenty (20) consecutive trading days
        immediately preceding the date which is five (5) days prior to the date
        of the Cash/Royalty Notice; and

               (b) Ligand shall have the right to designate either Targretin (as
        defined in that certain Development and License Agreement (Targretin)
        dated the date of this Agreement), Compound 268 or Compound 324 (each as
        defined in that certain Collaboration Agreement dated the date of this
        Agreement) for increased royalties, which right shall be exercised in
        the manner set forth and on the terms and conditions provided in Section
        5.1(b) of the Targretin Agreement with respect to 


                                       1






        Targretin, or Section 6.1(b) of the Collaboration Agreement with
        respect to Compound 268 or Compound 324.

        The Cash/Royalty Option shall terminate if not exercised before the
        Cash/Royalty Termination Date and thereafter the only option available
        under this Agreement shall be the Ligand Option."

        2.      All other terms and conditions of the Agreement shall remain in
full force and effect.

        3. As of the date of this Amendment, Lilly and Ligand have entered into
an Agreement (the "Lilly Agreement") which sets forth certain rights relating to
the Product. In the event of inconsistency between this Amendment and the Lilly
Agreement, the terms of the Lilly Agreement shall govern.

        4. This Amendment may be executed in two or more counterparts, each of
which shall be deemed an original, but all of which together shall constitute
one in the same.

                  [Remainder of Page Intentionally Left Blank]



                                       2








LIGAND PHARMACEUTICALS              ELI LILLY AND COMPANY
INCORPORATED

By:                                         By:
   -------------------------                      -------------------------
Title:                                      Title:
   -------------------------                      -------------------------

Date: May ___, 1998                         Date: May ___, 1998

























                      [SIGNATURE PAGE TO AMENDMENT NO. 3 TO

                    OPTION AND WHOLESALE PURCHASE AGREEMENT]


                                       3








                                                          May 11, 1998


Ligand Pharmaceuticals Incorporated
10275 Science Center Drive
San Diego, CA 92121

Ladies and Gentlemen:

     The undersigned is a stockholder of Seragen, Inc., a Delaware corporation
("Seragen"). The undersigned understands that Seragen, Ligand Pharmaceuticals
Incorporated, a Delaware corporation ("Ligand"), and Knight Acquisition
Corporation, a Delaware Corporation ("Merger Sub"), have entered into an
Agreement and Plan of Reorganization, dated as of May 11, 1998 (the
"Reorganization Agreement"), which provides for the merger (the "Merger") of
Merger Sub into Seragen. The undersigned also understands that Ligand, at its
option, may provide some or all of the Merger Consideration (as defined in the
Reorganization Agreemnt) in the form of shares of voting common stock, par
value $.001 per share, of Ligand (the "Common Stock"). The undersigned further
understands that the issuance of the Common Stock pursuant to the terms of the
Merger will be the subject of a registration statement under the Securities
Act of 1933, as amended (the "Registration Statement"), which will be filed
with the Securities and Exchange Commission and which will contain a prospectus
relating to the Merger (the "Prospectus").

     In consideration of the execution of the Reorganization Agreement by
Ligand and Merger Sub, and for other good and valuable consideration, the
receipt and adequacy of which are hereby acknowledged, the undersigned hereby
agrees that from the date of issuance of the Common Stock pursuant to the
Reorganization Agreement, if such issuance occurs, any shares of Common Stock
issued pursuant to the Reorganization Agreement (the "Merger Shares") shall
be subject to the transfer restrictions set forth in Section 4.1 of that
certain Stock Purchase Agreement dated November 25, 1997 between the
undersigned and Ligand (the "Purchase Agreement"), as if the Merger Shares
were Shares (as defined in the Purchase Agreement), for the periods of time
set forth in Section 4.1 of the Purchase Agreement.


     It is understood and agreed that the foregoing agreement is provided as 
an inducement to, and may be relied upon by, Ligand, Seragen and Merger Sub in 
connection with (a) their consummation of the Merger and (b) their preparation 
and distribution of the Registration Statement and the Prospectus.

     Seragen and Boston Equiserv, as transfer agent for Seragen, and Ligand and
ChaseMellon Shareholder Services LLC, as the transfer agent for Ligand, are
each hereby authorized to enforce the terms of this letter by refusing to permit
transfers of Common Stock which Ligand concludes may violate the terms of this
letter.





     This letter may be executed in one or more counterparts, each of which
shall be deemed an original, but all of which together shall constitute a single
instrument.


                                                  Sincerely,

                                                  ELI LILLY AND COMPANY

                                                  ------------------------------
                                                  Signature

                                                  ------------------------------
                                                  Printed Name

Accepted and agreed to as of the date first
written above:

LIGAND PHARMACEUTICALS INCORPORATED

By:
   -----------------------------------

Title:
      --------------------------------