Friday, Aug 2, 2002

Genentech and XOMA Announce Preliminary Data from Long-Term Study with Investigational Psoriasis Therapy

-- Companies Also Unveil New Product Trade Name RaptivaTM at AAD ACADEMY 2002 --

NEW YORK, NY, -- August 2, 2002 -- Genentech Inc. (NYSE: DNA) and XOMA Ltd. (Nasdaq: XOMA) announced today preliminary data from a long-term treatment study with their investigational psoriasis treatment Raptiva™ (efalizumab, formerly Xanelim™) in which 79.1 percent of the cohort of patients completing one year of Raptiva therapy (n=215) maintained 50 percent or greater improvement in Psoriasis Area and Severity Index (PASI) scores (PASI 50). Sixty-one percent of this cohort had 75 percent or greater PASI improvement (PASI 75) after one year of therapy.

The data from this study will be presented by Craig Leonardi, M.D., Clinical Associate Professor at St. Louis University Medical School, on Saturday, August 3 at a general psoriasis session at the American Academy of Dermatology's (AAD) ACADEMY 2002 meeting. Genentech and XOMA also announced that the companies have elected to change the product's trade name from Xanelim to Raptiva in order to limit potential confusion with an already existing drug.

Preliminary Data from Long-Term Study with Raptiva

The preliminary data are from an open-label, long-term trial with Raptiva, in which 339 patients received an initial three-month course of therapy consisting of weekly subcutaneous doses of 2 mg/kg of Raptiva. After the initial three months of treatment, 85 percent (n=288) of patients achieved PASI 50 or an Overall Lesion Severity score (OLS) of "Mild." These patients were entered into an extended treatment phase in which they received weekly doses of 1 mg/kg of Raptiva, with a provision for return to 2 mg/kg under some circumstances. For each successive 3 month period of treatment, dropouts during that cohort period were counted as non-responders for that cohort, but were excluded from the subsequent cohorts.

All 288 subjects entering the extended treatment phase were first assessed for maintenance of PASI improvements at 6 months, i.e. after 3 months of extended treatment. Preliminary analysis showed that at 6 months, 77.1 percent of 288 patients had maintained PASI 50 and 51 percent of these patients had PASI 75. To date, of the cohort completing 9 months (n=265), 80.5 percent maintained PASI 50 and 58 percent had PASI 75. Of the cohort completing one year (n=215), 79.1 percent maintained PASI 50 and 61 percent had PASI 75.

"Given that psoriasis is a chronic disease, it's important that we understand more about Raptiva's activity over extended treatment periods," said Dr. Leonardi. "The final results from this study will provide additional information about using Raptiva in longer-term clinical settings."

Safety data from the first 12 weeks of therapy showed that the most common adverse events (occurring in approximately 10 percent or more of patients) included headache, non-specific infection (e.g., the common cold), chills, pain, nausea, asthenia (loss of strength), and fever.

Multiple Symptom Scale Assessment Results

In addition to the long-term study data, poster presentations at the meeting highlight further data from the two Phase III trials of Raptiva in moderate-to-severe psoriasis patients, focusing on safety and symptom relief measurement. Multiple scales, including the National Psoriasis Foundation (NPF) Psoriasis Score, Dermatology Life Quality Index (DLQI) and the Psoriasis Symptom Assessment (PSA) scale were used to evaluate symptoms affecting psoriasis and dermatology-related quality of life issues and yielded encouraging results which paralleled improvements in PASI scores.

About Raptiva

Raptiva is a targeted T-cell modulator that is designed to inhibit the binding of T-cells to other cell types and target three key processes in the cascade of events that lead to psoriasis. These processes are: (1) binding of T-cells through interactions with adhesion molecules on the endothelial cell surface; (2) migration of T-cells into the skin; and (3) activation of T-cells, all of which may be linked to the abnormal growth of skin cells and the painful, elevated scaly patches of skin (lesions) typical among psoriasis sufferers.

Psoriasis Background

Psoriasis is a chronic skin disease that affects more than four and a half million Americans (about 2.1 percent of the U.S. population), according to the National Psoriasis Foundation. Psoriasis occurs when new skin cells grow abnormally, resulting in thick, red, scaly, inflamed patches. Plaque psoriasis, the most common form of the disease, is characterized by inflamed patches of skin ("lesions") topped with silvery white scales. Psoriasis can be limited to a few spots or involve extensive areas of the body, appearing most commonly on the scalp, knees, elbows and trunk. Although it is highly visible, psoriasis is not a contagious disease. While there are a number of medications that may help control the symptoms of psoriasis, there currently is no known cure.

Genentech is a leading biotechnology company that discovers, develops, manufactures and commercializes biotherapeutics for significant unmet medical needs. Fifteen of the currently approved biotechnology products originated from or are based on Genentech science. Genentech manufactures and commercializes 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. XOMA's programs include collaborations: with Genentech, Inc. on the Raptiva™; antibody for psoriasis (Phase III), rheumatoid arthritis (Phase II) and other indications; with Onyx Pharmaceuticals, Inc. to develop and manufacture its ONYX-015 product for various cancers (Phase II and III); with Baxter Healthcare Corporation to develop NEUPREX┬« (rBPI-21) for Crohn's disease (Phase II) and other indications; and with Millennium Pharmaceuticals, Inc. on two biotherapeutic agents, CAB2 and MLN01, for certain vascular inflammation indications (preclinical). Earlier-stage development programs include compounds to treat cancer, retinopathies, autoimmune diseases and infections. For more information about XOMA's pipeline and activities, please visit XOMA's website at

Statements made in this news release related to the progress of clinical trials and timing of product development, 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 the timing and results of pending or future clinical trials, changes in the status of the Company's collaborative and other relationships, the ability of collaborators and other partners to meet their obligations, the success of competitors, market demand for products, actions by the Food and Drug Administration or the U.S. Patent and Trademark Office, and uncertainties regarding biotechnology patents, are discussed in the Company's most recent annual report on Form 10-K and in other SEC filings. Consider such risks carefully in evaluating XOMA's prospects.