XOMA Presents Data On XOMA 052, An Anti-IL-1 Beta Antibody, in Rheumatoid Arthritis and Acute Gout Animal Models

BERKELEY, Calif., Oct. 25, 2008 (GLOBE NEWSWIRE) -- XOMA Ltd. (Nasdaq:XOMA), a leader in the discovery and development of antibody therapeutics, today announced that its poster titled "Efficacy Of XOMA 052 Anti-IL-1 Beta Antibody In The DBA/1 Mouse Collagen-Induced Arthritis Model" will be presented at the American College of Rheumatology 2008 Annual Conference, on Sunday, October 26 from 9:00 AM until 11:00 AM in Hall A. The poster also contains data demonstrating that XOMA 052 blocks inflammation in a mouse model of acute gout.

Rheumatoid arthritis (RA) is a chronic autoimmune disorder wherein the cells of the immune system attack the joints, causing inflammation and joint destruction. Approximately 1.3 million adults in the U.S. have been diagnosed with rheumatoid arthritis. Gout is a disease caused by the buildup of uric acid in the cartilage of joints, tendons and surrounding tissues. In acute attacks of gout, uric acid generates inflammation which can cause excruciating and sudden pain. Gout afflicts approximately 3 million people in the U.S. Both disease processes are associated with IL-1, and the data support clinical trial testing of XOMA 052 in RA and acute gout.

About XOMA 052

XOMA 052 is a potent monoclonal antibody with the potential to improve the treatment of patients with a wide variety of inflammatory diseases. XOMA 052 binds strongly to Interleukin-1 beta (IL-1 beta), a pro-inflammatory cytokine that is involved in the development of diabetes, rheumatoid arthritis, gout, and other diseases. By binding IL-1 beta, the drug blocks the activation of the IL-1 receptor, thereby preventing the cellular signaling events that produce inflammation. Data from an ongoing clinical study of XOMA 052 in Type 2 diabetes patients showed that the drug candidate improved glucose control, increased insulin production and reduced systemic inflammation. XOMA 052 is a humanized IgG2 antibody with a half-life of 22 days. Based on its binding properties, specificity to IL-1 beta and half-life, XOMA 052 may provide convenient dosing of once per month or longer. XOMA 052 was developed by XOMA using the Company's proprietary antibody technologies, capabilities and expertise. XOMA owns worldwide rights to the antibody and related intellectual property.

About XOMA

XOMA is a leader in the discovery, development and manufacture of therapeutic antibodies. The Company's expanding pipeline includes XOMA 052, an anti-IL-1 beta antibody, and XOMA 629, a synthetic peptide compound derived from bactericidal/permeability-increasing protein.

XOMA's proprietary development pipeline is primarily funded by multiple revenue streams resulting from the licensing of its antibody technologies, product royalties, development collaborations, and biodefense contracts. XOMA's technologies and experienced team have contributed to the success of marketed antibody products, including RAPTIVA(r) (efalizumab) for chronic moderate to severe plaque psoriasis and LUCENTIS(r) (ranibizumab injection) for wet age-related macular degeneration.

The Company has a premier antibody discovery and development platform that incorporates leading antibody phage display libraries and XOMA's proprietary Human Engineering(tm) and bacterial cell expression (BCE) technologies. BCE is a key breakthrough biotechnology for the discovery and manufacturing of antibodies and other proteins. As a result, more than 50 pharmaceutical and biotechnology companies have signed BCE licenses.

In addition to developing its own products, XOMA develops products for premier pharmaceutical companies including Novartis AG, Schering-Plough Research Institute and Takeda Pharmaceutical Company Limited. XOMA has a fully integrated product development infrastructure, extending from pre-clinical science to product launch, and a team of 330 employees at its Berkeley location. For more information, please visit http://www.xoma.com.

Certain statements contained herein relating to 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 results of discovery research and preclinical testing; the timing or results of pending and future clinical trials (including the design and progress of clinical trials; safety and efficacy of the products being tested; action, inaction or delay by the FDA, European or other regulators or their advisory bodies; and analysis or interpretation by, or submission to, these entities or others of scientific data); uncertainties regarding the status of biotechnology patents; uncertainties as to the cost of protecting intellectual property; changes in the status of the existing collaborative and licensing relationships; the ability of collaborators, licensees and other third parties to meet their obligations; market demand for products; scale up and marketing capabilities; competition; international operations; share price volatility; XOMA's financing needs and opportunities; and risks associated with XOMA's status as a Bermuda company, are described in more detail in XOMA's most recent annual report on Form 10-K and in other SEC filings. Consider such risks carefully in considering XOMA's prospects.

CONTACT: XOMA Ltd.
         Greg Mann
         510-204-7270
         mann@xoma.com

         Porter Novelli Life Sciences
         Media & Investors Contact:
         Carolyn Hawley
         619-849-5375
         chawley@pnlifesciences.com

Released October 25, 2008