XOMA 052 Mechanism of Action Results Published in Journal of Biological Chemistry

BERKELEY, Calif., April 30, 2010 (GLOBE NEWSWIRE) -- XOMA Ltd. (Nasdaq:XOMA), a leader in the discovery and development of therapeutic antibodies, announced the publication of a peer-reviewed paper describing the novel mechanism of action of XOMA 052, a potent, high affinity antibody that inhibits the inflammatory cytokine interleukin-1 beta (IL-1 beta) while having no effect on the binding of IL-1 beta to the decoy receptors that clear excess IL-1 beta from the body. XOMA 052 is currently in Phase 2 development for the treatment of patients with Type 2 diabetes, Type 1 diabetes and cardiovascular disease. The paper is expected to be included in the June 2010 issue of the Journal of Biological Chemistry, and has been published online at http://www.jbc.org/content/early/2010/04/21/jbc.M110.115790.full.pdf+html?sid=feb559be-278f-42fc-92be-e4f00cf2891a .

"This publication adds to the rapidly expanding body of scientific literature in the IL-1 field. We are pleased that the editors of the well-regarded Journal of Biological Chemistry recognized its importance," said Patrick J. Scannon, M.D., Ph.D., XOMA's Executive Vice President and Chief Medical Officer.

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 IL-1 beta, a pro-inflammatory cytokine involved in the development of Type 2 diabetes, cardiovascular disease, rheumatoid arthritis, gout and other diseases. By binding to IL-1 beta, XOMA 052 inhibits the activation of the IL-1 receptor, thereby preventing the cellular signaling events that produce inflammation. Based on its binding properties, specificity to IL-1 beta and half-life, XOMA 052 may provide convenient dosing of once per month or less frequently.

About XOMA

XOMA discovers, develops and manufactures novel antibody therapeutics for its own proprietary pipeline as well as through license and collaborative agreements with pharmaceutical and biotechnology companies, and under its contracts with the U.S. government. The company's proprietary product pipeline includes:

  --  XOMA 052, an antibody to IL-1 beta in Phase 2 clinical development for
      Type 2 diabetes, Type 1 diabetes and cardiovascular disease, with
      potential for the treatment of a wide range of inflammatory conditions.
  --  XOMA 3AB, an antibody candidate in pre-IND studies to neutralize the
      botulinum toxin, among the most deadly potential bioterror threats,
      under development through funding provided by the National Institute of
      Allergy and Infectious Diseases of the National Institutes of Health
      (Contract # HHSN266200600008C).
  --  A preclinical pipeline with candidates in development for several
      diseases.

In addition to its proprietary pipeline, XOMA develops products with premier pharmaceutical companies including Novartis AG, Schering Corporation, a subsidiary of Merck & Co., Inc. and Takeda Pharmaceutical Company Limited.

XOMA's technologies 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 an unmatched collection of antibody phage display libraries and proprietary Human Engineering(TM), affinity maturation, Bacterial Cell Expression (BCE) and manufacturing 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, and several licensed product candidates are in clinical development.

XOMA has a fully integrated product development infrastructure, extending from pre-clinical science to approval, and a team of about 200 employees at its Berkeley, California 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

Safe Harbor Statement

Certain statements contained herein concerning conduct or availability of results of clinical trials, entry into a XOMA 052 development partnership or potential licensing and collaboration arrangements or other aspects 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.

Among other things, the conduct or availability of results of clinical trials may be impacted by, or delayed or may never occur as a result of, unavailability of resources, actions or inaction by our present or future collaboration partners, insufficient enrollment in such trials or unanticipated safety issues; and a XOMA 052 partnership may not be entered into in the timeframes indicated or at all.

These and other risks, including those related to the ability to comply with NASDAQ's continued listing requirements; the generally unstable nature of current economic conditions; 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.
          Company and Investor Contact:
          Carol DeGuzman
          510-204-7270
          deguzman@xoma.com

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