Thursday, Oct 4, 2001

Genentech and Xoma Update Xanelim BLA Filing Timing

South San Francisco and Berkeley, Calif. -- October 4, 2001 --

Genentech Inc. (NYSE: DNA) and XOMA Ltd. (Nasdaq: XOMA) announced that an additional pharmacokinetics study, to be included in the potential Biologics License Application (BLA) submission to the U.S. Food and Drug Administration (FDA) for Xanelim™ (Efalizumab), will delay the estimated filing date to summer 2002.During Phase III Xanelim testing, minor manufacturing modifications were made to allow for large-scale material production. These modifications were discussed with and agreed to by the FDA. Recently the agency requested that a pharmacokinetic study be completed to confirm head-to-head equivalence between the Xanelim material used for clinical testing and the Xanelim material planned for large-scale manufacturing. Genentech and XOMA will initiate this study shortly and anticipate filing the BLA pending successful study completion.

Genentech, Inc. is a leading biotechnology company that discovers, develops, manufactures and markets human pharmaceuticals for significant unmet medical needs. Fifteen of the currently approved biotechnology products stem from or are based on Genentech science. Genentech markets ten biotechnology products directly in the United States. The company has headquarters in South San Francisco, California and is traded on the New York Stock Exchange under the symbol DNA.

XOMA develops and manufactures innovative biopharmaceuticals for disease targets that include cancer, immunological and inflammatory disorders and infectious diseases. In addition to the Genentech Xanelim collaboration, late-stage programs include collaborations with Baxter Healthcare Corporation to develop NEUPREX™ (rBPI-21) for multiple indications (Phase II and III), and Onyx Pharmaceuticals, Inc. to develop and manufacture its CI-1042 product for cancer (Phase II and III). Earlier-stage development programs include compounds for cancer, autoimmune diseases, infections and retinopathies. For more information about XOMA's pipeline and activities, please visit the Company's web site at http://www.xoma.com.

###

Statements made in this news release related to collaborative agreements and current plans for product development, including the progress of clinical trials and the timing of regulatory filings, or that otherwise relate to future periods, are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. These statements are based on assumptions that may not prove accurate. Actual results could differ materially from those anticipated due to certain risks inherent in the biotechnology industry and for companies engaged in the development of new products in a regulated market. These risks, including those related to changes in the status of existing collaborative relationships, the timing or results of pending and future clinical trials, the ability of collaborators and other partners to meet their obligations, market demand for products, actions by the Food and Drug Administration or the U.S. Patent and Trademark Office and uncertainties regarding the status of biotechnology patents, are discussed in XOMA's most recent annual report on Form 10-K and in other SEC filings. Consider such risks carefully in evaluating XOMA's prospects.

# # #