Friday, Mar 21, 2003

Phase III Study Results with Raptiva in the Treatment of Psoriasis Presented at Annual AAD Meeting

South San Francisco, Calif. -- March 21, 2003 --

Genentech, Inc. (NYSE: DNA) and XOMA Ltd. (Nasdaq: XOMA) today announced positive results from a randomized Phase III clinical trial with Raptiva™ (efalizumab) that studied efficacy and safety in the treatment of adults with moderate-to-severe plaque psoriasis. The study results were presented by Kenneth Gordon, M.D., Associate Professor of Medicine, Division of Dermatology at Loyola University in Chicago, Illinois during a session on emerging biologic therapies for psoriasis at the 61st annual American Academy of Dermatology (AAD) meeting in San Francisco.

Results from the 556-patient, placebo-controlled study were consistent with data obtained from previous Phase III Raptiva studies and were included as part of a Biologics License Application (BLA) to the U.S. Food and Drug Administration and are currently under review. After 12 weeks of Raptiva therapy, 27 percent (98/369) of study patients demonstrated 75 percent or greater Psoriasis Area and Severity Index (PASI) score improvement, versus 4 percent (8/187) of patients on placebo, and 59 percent (216/369) achieved 50 percent or greater PASI score improvement, versus 14 percent (26/187) in the placebo group.

"Our extensive clinical experience with Raptiva in three randomized Phase III trials and a long-term open-label trial demonstrate that patients experience clinically meaningful response with rapid onset of effect," said Hal Barron, M.D., FACC, Genentech's vice president, Medical Affairs. "We believe that these efficacy results combined with the emerging safety profile in more than 2,100 Raptiva-treated patients contribute to a favorable overall clinical profile for Raptiva as a potential once-weekly treatment for moderate-to-severe psoriasis."

Data from 15 months of an open-label multicenter trial evaluating the safety and tolerability of Raptiva as a potential continuous treatment in patients with moderate-to-severe psoriasis will be presented by Alice Gottlieb, M.D., director of the Clinical Research Center at the Robert Wood Johnson Medical School at the University of Medicine and Dentistry of New Jersey on Saturday, March 22.

Efficacy and Quality of Life Data Presented
In the double blind, placebo-controlled, multicenter study, 556 patients were randomized in a 2 to 1 ratio to receive weekly subcutaneous doses of 1 mg/kg Raptiva (n=369) or placebo (n=187) for a 12-week period. The study's primary endpoint was to compare the percentage of patients who achieved 75 percent or greater improvement in PASI scores (PASI 75) after 12 weeks of Raptiva therapy with patients receiving placebo. Secondary endpoints include the percentage of patients who achieved 50 percent or greater improvement in PASI scores (PASI 50); the Overall Lesion Severity scale (OLS), which is a static measure of global physician assessment on psoriasis; patient-reported outcomes such as the Dermatology Life Quality Index (DLQI), which measures impairment from a skin condition, and the Psoriasis Symptom Assessment (PSA).

At week 12, mean improvement in DLQI scores with Raptiva treatment was 47 percent, versus 14 percent for patients on placebo. The study results with Raptiva showed improvement on each of the eight PSA subsets: pain, burning or stinging, itching, bothered by water, irritation, sensitivity, bleeding and scaling.

"The reduction in disease severity and rapid onset of action observed in Raptiva-treated study patients along with the positive impact on these patients' quality of life measurements provide further support for Raptiva as a potential treatment option for psoriasis patients," said Dr. Gordon.

Adverse events that occurred at least 5% more frequently in patients receiving Raptiva compared with those in the placebo group included headache, chills, pain, fever, and myalgia (muscle pain). These events occurred principally following the first two injections of Raptiva. For the third and subsequent doses, the incidence of acute adverse events was similar between the Raptiva and placebo groups. The only serious unexpected adverse event reported as study drug related by the investigators was one case of myelitis.

About Raptiva™
As a targeted T-cell modulator, Raptiva (efalizumab) is designed to block the activation of disease fighting T-cells that cause psoriasis, without destroying them. Raptiva has been studied as a once-weekly therapy for the continuous treatment of moderate-to-severe plaque psoriasis. In clinical trials, Raptiva was administered via subcutaneous injection and in several of the trials was self-administered by some patients in their homes. In December 2002, Genentech and XOMA filed a Biologics License Application (BLA) with the U.S. Food and Drug Administration for Raptiva for the treatment of moderate-to-severe plaque psoriasis in patients 18 years or older. The BLA submission included data from over 2,100 patients with moderate-to-severe plaque psoriasis treated with Raptiva.

About Psoriasis
Psoriasis occurs when new skin cells grow abnormally, resulting in thick, red, scaly, inflamed patches. Plaque psoriasis, the most common form of the disease, affects approximately 2.3 million Americans, and 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.

About Genentech
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.

About XOMA
XOMA develops and manufactures antibody and other protein-based 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 (BLA submission), rheumatoid arthritis (Phase II), psoriatic arthritis (Phase II) and other indications; with Baxter Healthcare Corporation to develop NEUPREX® (rBPI21) for Crohn's disease (Phase II) and other indications; with Millennium Pharmaceuticals, Inc. on two biotherapeutic agents, CAB2 and MLN01, for certain vascular inflammation indications (preclinical); and with Onyx Pharmaceuticals, Inc. on its ONYX-015 product for various cancers (current activities suspended, pending partnership discussions). 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 http://www.xoma.com/.

Regarding XOMA:
Statements made in this news release related to the regulatory process and collaborative arrangements, 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 include those related to safety and efficacy of the products being studied; action, inaction or delay by the Food and Drug Administration and European regulators; analysis, interpretation and submission of scientific data; changes in the status of existing collaborative relationships; the ability of collaborators to meet their obligations and market demand for products. These risks are discussed in XOMA?s most recent annual report on Form 10K and in other SEC filings. Consider such risks carefully in evaluating XOMA?s prospects.