Exhibit 10.160 SEVENTH ADDENDUM TO AMENDED REGISTRATION RIGHTS AGREEMENT _________________________________________________________ This Seventh Addendum ("Addendum") to the Amended Registration Rights Agreement dated June 24, 1994, as amended through the date hereof ("Registration Rights Agreement") between Ligand Pharmaceuticals Incorporated (the "Company") and S.R. One, Limited ("Investor") is effective as of November 10, 1995. RECITALS A. As of the date hereof, the Company has issued 260,200 shares of the Company's Common Stock (the "Shares") to Investor pursuant to Section 1.1(b) of that certain Stock and Note purchase Agreement dated February 3, 1995 among the Company, Investor and Smith Kline Beecham Corporation (the "Purchase Agreement"). B. This Addendum serves to include the Shares within the definition of "Registrable Securities" under the Registration Rights Agreement and to modify Schedule A to the Registration Rights Agreement to include such Shares, all pursuant to Section 2.6(a) of the Registration Rights Agreement. NOW, THEREFORE, in consideration of the mutual promises and covenants set forth in the Registration Rights Agreement, the parties agree as follows: 1. Section 1.1, paragraph (f) of the Registration Rights Agreement is hereby restated in its entirety as follows: "(f) The term "Registrable Securities" means (i) the 1,939,435 shares of Class A Common Stock and 5,818,362 shares of Class B Common Stock (or that number of shares of such other class of stock into which the Class A Common Stock and Class B Common Stock are converted) issued upon conversion of the Company's Preferred Stock to the holders thereof and in the amounts set forth on Schedule A attached hereto, (ii) the Common Stock issuable or issued upon exercise of those warrants issued to certain Existing Investors and pursuant to which such Existing Investors were previously granted registration rights by the Company (iii) the 429,553 shares of Class A Common Stock (or that number of shares of such other class of stock into which the Class A Common Stock is converted) issued to Abbott Laboratories pursuant to a Stock Purchase Agreement dated July 6, 1994 which shares are reflected on Schedule A attached to the First Addendum to this Agreement, (iv) the 431,965 shares of Class A Common Stock (or that number of shares of such other class of stock into which the Class A Common Stock is converted) issued to American Home Products Corporation pursuant to a Stock and Note Purchase Agreement dated September 2, 1994 which shares are reflected on Schedule A attached to the Second Addendum to this Agreement, and the shares of Class A Common Stock (or the shares of such other class of stock into which the Class A Common Stock is converted) issuable upon conversion of those certain Unsecured Convertible Promissory Notes issued to American Home Products Corporation pursuant to the Stock and Note Purchase Agreement (and upon such conversion of the Notes, Schedule A shall be updated to include such shares), (v) the 674,127 shares of Common Stock (formerly Class B Common Stock prior to conversion of Class A Common Stock into Class B Common Stock and the renaming of all outstanding shares of Class B Common Stock pursuant to the Corporation's Certificate of Designation) issued to Investor pursuant to the Purchase Agreement which shares are reflected on Schedule A attached to the Third Addendum to this Agreement, (vi) the 35,957 shares of Common Stock issuable or issued upon exercise of the Warrant issued to Genentech, Inc. in connection with the merger of L.G. Acquisition Corp., a wholly-owned subsidiary of the Company, with and into Glycomed Incorporated, which shares are reflected on Schedule A attached to the Fourth Addendum to this Agreement, (vii) the 189,274 shares of Common Stock (or that number of shares of such other class of stock into which the Common Stock is converted) issued to Sankyo Company Limited pursuant to a Stock Purchase Agreement dated June 28, 1995 which shares are reflected on Schedule A attached to the Fifth Addendum to this Agreement, (viii) the 516,129 shares of Common Stock (or that number of shares of such other class of stock into which the Common Stock is converted) issued to Abbott Laboratories pursuant to a Stock Purchase Agreement dated August 28, 1995 which shares reflected on Schedule A attached to the Sixth Addendum to this Agreement, (ix) the 260,200 shares of Common Stock (or that number of shares of such other class of stock into which the Common Stock is converted) issued to the Investor pursuant to the Purchase Agreement which shares are reflected on Schedule A attached to the Seventh Addendum to this Agreement, and (x) any Common Stock of the Company issued as (or issuable upon the conversion or exercise of any warrant, right or other security which is issued as) a dividend or other distribution with respect to, or in exchange for or in replacement of the shares referenced in (i), (ii), (iii), (iv), (v), (vi), (vii), (viii), and (ix) above, excluding in all cases, however, any Registrable Securities sold by a person in a transaction in which rights under this Agreement are not assigned." 2. Schedule A of the Registration Rights Agreement is hereby restated in its entirety as attached to this Addendum. 3. This Addendum may be executed in one or more counterparts. 4. This Addendum shall be binding upon the Company, Investor and each holder of Registrable Securities and each future holder of Registrable Securities pursuant to Section 2.6(a) of the Registration Rights Agreement. IN WITNESS WHEREOF, the parties have executed this Addendum as of the date first above written. S.R. ONE, LIMITED LIGAND PHARMACEUTICALS INCORPORATED By: /s/ By: /s/ __________________________ ___________________________ William L. Respess Title: Vice President Title: Senior Vice President, General Counsel, Government Affairs SCHEDULE A __________ To Seventh Addendum to Amended Registration Rights Agreement LIGAND PHARMACEUTICALS INCORPORATED Common Stock Registered Name Of: Shares ====================================================================== Abbott Laboratories 516,129 Abbott Laboratories 571,305 Alexander D. Cross, Trustee, O.A., dated 7/8/91 11,275 Allergan Pharmaceuticals (Ireland) Ltd., Inc. 1,353,125 American Home Products Corporation 574,513 Enterprise Partners 774,766 Genentech, Inc. 35,957 Glaxo Inc. 662,755 Kleiner Perkins Caufield & Byers IV 1,553,469 KPCB Zaibatsu 36,082 ML Venture Partners II, L.P. 499,858 Levy, David 8,119 New York University 8,119 Pfizer Inc 1,353,125 Respess, William 901 Rockefeller 101,250 S.R. One, Limited 674,127 S.R. One, Limited 260,200 Sankyo Company Limited 189,274 Senyei, Andrew 11,275 ====================================================================== TOTAL 9,195,624