XOMA Royalties On CIMZIA(r) Expected to Increase Due to FDA Approval for Moderate to Severe Rheumatoid Arthritis in Adults

BERKELEY, Calif., May 14, 2009 (GLOBE NEWSWIRE) -- XOMA Ltd. (Nasdaq:XOMA), a leader in the discovery and development of antibody therapeutics, announced today that its bacterial cell expression (BCE) technology licensee UCB S.A. has received FDA approval to market CIMZIA(r) (certolizumab pegol), an anti-tumor necrosis factor product, for the treatment of moderate to severe rheumatoid arthritis (RA) in adults. XOMA will receive royalty payments on sales of CIMZIA for this indication and will continue to receive royalties on sales of CIMZIA for the treatment of moderate to severe Crohn's disease, for which it was approved in April 2008.

Bacterial cell expression, a component of XOMA's premier antibody discovery and development platform, is a key enabling 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.

According to UCB, approximately 1.3 million Americans suffer from rheumatoid arthritis and Crohn's disease afflicts approximately 500,000 people in the U.S.

About XOMA

XOMA discovers, develops and manufactures therapeutic antibody and other agents designed to treat inflammatory, autoimmune, infectious and oncological diseases. The Company's proprietary product pipeline includes XOMA 052, an anti-IL-1 beta antibody, and XOMA 3AB, a biodefense anti-botulism antibody candidate.

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 LUCENTIS(r) (ranibizumab injection) for wet age-related macular degeneration and CIMZIA(r) (certolizumab pegol) for rheumatoid arthritis and Crohn's disease.

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 and manufacturing technologies. Bacterial cell expression 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 with premier pharmaceutical companies including Novartis AG, Schering-Plough Research Institute and Takeda Pharmaceutical Company Limited. XOMA has a fully integrated product development infrastructure and a team of 200 employees at its Berkeley location. For more information, please visit http://www.xoma.com.

The XOMA Ltd. logo is available at https://www.globenewswire.com/newsroom/prs/?pkgid=5960

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
          Carol DeGuzman
          510-204-7270
          deguzman@xoma.com

Released May 14, 2009