press release archive

Rigel’s R788 Shows Preclinical Activity in Type 1 Diabetes Model

Research To Be Presented at American Association of Immunologists Meeting

SOUTH SAN FRANCISCO, Calif. - April 08, 2008

Rigel Pharmaceuticals, Inc. (Nasdaq: RIGL) today announced that its oral Syk kinase inhibitor, R788, may be a useful treatment for type 1 diabetes mellitus, according to research being presented at the American Association of Immunologists meeting in San Diego, California on April 8, 2008. Using Rigel’s R788, researchers from the Department of Medicine at Columbia University Medical Center have shown that blocking Syk kinase in a well-established murine model of type 1 diabetes, delayed the onset of diabetes and prolonged survival. A reduction in the production of insulin-specific autoantibodies, an early event in type 1 diabetes pathogenesis, was also observed.

“Inhibition of the Syk kinase has the potential to reduce both autoantibody production and disarm its pathogenic consequences,” said Raphael Clynes M.D., Ph.D., assistant professor in Medicine and Microbiology at Columbia University’s College of Physician’s and Surgeons. “In diabetes, autoantibodies against islet cells appear before the actual onset of disease providing the opportunity to intervene and disable these early events prior to immune destruction of the insulin-producing cells in the pancreas. The protection we see in these mouse models suggests that pharmacologic blockade of Syk with R788 may provide a good therapeutic strategy to treat and potentially prevent the onset or advancement of type 1 diabetes,” he added.

Type 1 Diabetes and R788
According to the Juvenile Diabetes Research Foundation, type 1 diabetes, also called juvenile diabetes or insulin-dependent diabetes, occurs when the body’s immune system attacks and destroys beta cells within the islets of the pancreas. Beta cells normally produce insulin, a hormone that helps the body move glucose from food into the body’s cells to be used for energy. If insulin cannot be produced, the glucose remains in the blood and ultimately may damage organs and tissues. Therefore, insulin replacement via injection once or more each day is vital to patients with type 1 diabetes.

Extensive studies of Rigel’s oral Syk inhibitor, R788, have demonstrated results indicating its potential value in modulation of the immune response in a variety of autoimmune disorders. As such, R788 is presently in clinical trials for rheumatoid arthritis, immune thrombocytopenic purpura, and B-cell lymphoma.

This work was supported by funds provided by the Juvenile Diabetes Research Foundation and the Naomi Berrie Diabetes Center at Columbia University Medical Center in Manhattan.

Note: R788 is a prodrug of R406, which is cited in the research study.

About Rigel (www.rigel.com)
Rigel is a clinical-stage drug development company that discovers and develops novel, small-molecule drugs for the treatment of inflammatory/autoimmune diseases and cancer, as well as viral and metabolic diseases. Our goal is to file one new investigational new drug (IND) application in a significant indication each year. Rigel has achieved this goal every year since 2002. Our pioneering research focuses on intracellular signaling pathways and related targets that are critical to disease mechanisms. Rigel's productivity has resulted in strategic collaborations with large pharmaceutical partners to develop and market our product candidates. Rigel has product development programs in inflammatory/autoimmune diseases such as rheumatoid arthritis, thrombocytopenia and asthma, as well as in cancer.

This press release contains "forward-looking" statements, including statements related to the preclinical data and plans, the potential efficacy and commercial potential of R788 and Rigel's plans to pursue further preclinical development thereof. Any statements contained in this press release that are not statements of historical fact may be deemed to be forward-looking statements. Words such as “believe,” “may,” "expect," "potential," “indicate,” suggest,” and similar expressions are intended to identify these forward-looking statements. There are a number of important factors that could cause Rigel's results to differ materially from those indicated by these forward-looking statements, including risks associated with the timing and success of clinical trials and the commercialization of product candidates, potential problems that may arise in the clinical testing and approval process and Rigel's need for additional capital, as well as other risks detailed from time to time in Rigel's SEC reports, including its Form 10-K for the year ended December 31, 2007. Rigel does not undertake any obligation to update forward-looking statements.

Contact: Raul Rodriguez
Phone: 650.624.1302
Email: rrodriguez@rigel.com

Media Contact: Susan C. Rogers, Alchemy Consulting, Inc.
Phone: 650.430.3777
Email: susan@alchemyemail.com