UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 AMENDMENT NO. 1 on FORM 8-K/A CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of Earliest Event Reported): December 18, 2003 XOMA LTD. -------------------------------------------------------------------------------- (Exact name of registrant as specified in its charter) BERMUDA -------------------------------------------------------------------------------- (State or other jurisdiction of incorporation) 0-14710 52-2154066 (Commission File Number) (IRS Employer Identification No.) 2910 Seventh Street, Berkeley, California 94710 -------------------------------------------------------------------------------- (Address of principal executive offices) (Zip code) Registrant's telephone number, including area code (510) 204-7200 ----------------------------- -------------------------------------------------------------------------------- (Former name or former address, if changed since last report) Item 5. Other Events As announced on December 18, 2003, Alexion Pharmaceuticals, Inc. and XOMA Ltd. agreed to collaborate for the development and commercialization of an antibody to treat chemotherapy-induced thrombocytopenia. A copy of the press release is attached hereto as Exhibit 1 and is incorporated herein by reference. A copy of the agreement governing the collaboration is attached hereto as Exhibit 2 and incorporated herein by reference. Item 7. Exhibits 1. Press Release dated December 18, 2003. * 2. Co-Development and Co-Commercialization Agreement, dated as of December 17, 2003, by and between Alexion Pharmaceuticals, Inc. and XOMA (US) LLC (with certain confidential information omitted, which omitted information is the subject of a confidential treatment request and has been filed separately with the Securities and Exchange Commission). ___________________ * Previously filed. SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. Dated: January 9, 2004 XOMA LTD. By: /s/ Christopher J. Margolin ---------------------------------- Christopher J. Margolin Vice President, General Counsel and Secretary EXHIBIT INDEX Number Description ------ ----------- 1. Press Release dated December 18, 2003. * 2. Co-Development and Co-Commercialization Agreement, dated as of December 17, 2003, by and between Alexion Pharmaceuticals, Inc. and XOMA (US) LLC (with certain confidential information omitted, which omitted information is the subject of a confidential treatment request and has been filed separately with the Securities and Exchange Commission). ___________________ * Previously filed.