press release archive

Rigel Secures Hepatitis C Virus License Agreement from Chiron Corporation

South San Francisco, CA - November 03, 2003

Rigel Pharmaceuticals, Inc. (NASDAQ: RIGL) today announced that it has entered into a nonexclusive licensing agreement with Chiron Corporation (NASDAQ: CHIR) granting Rigel a license to discover, develop and commercialize small molecule therapeutics against certain hepatitis C virus (HCV) drug targets. The financial terms and other details of the license were not disclosed.

“Today’s agreement provides Rigel with the flexibility to pursue our innovative HCV research program and develop potential breakthrough treatments for HCV,” stated James M. Gower, chairman and chief executive officer. “We believe that Rigel’s lead drug candidate, R803, has the potential to become an anchor of therapeutic approaches to treating this intractable virus.”

The prevalence of HCV infection in the United States has been estimated at nearly 4 million, with approximately 170 million infected worldwide.1 Rigel’s lead HCV small-molecule drug candidate, R803, rapidly and selectively targets HCV and potentially stops replication of the virus by interfering with the viral polymerase, a protein needed for viral replication. Rigel believes that R803 will be one of the first direct antivirals to enter development and is substantially different from interferon alpha, the main current therapy, which primarily works indirectly to boost the immune system.

Rigel HCV Analyst/Investor Briefing
Rigel will host an analyst/investor day on Wednesday, November 19, 2003, at 10:00 a.m. Eastern Time at the W Hotel in New York City. The day will be devoted to the topic, “Hepatitis C: Treatment, Progress and Opportunities.” Featured speakers will include: Jules L. Dienstag, M.D., professor of medicine, associate dean for Academic and Clinical Programs, Harvard Medical School; Charles M. Rice, Ph.D., Maurice R. and Corinne P. Greenberg professor, and head, Laboratory of Virology and Infectious Disease, The Rockefeller University; and Rigel Senior Management. For additional information or to RSVP for the analyst day please email: hepc@rigel.com; call: (650) 624-1181; or visit Rigel’s Website at http://www.rigel.com/hepc.

About Rigel (www.rigel.com)
Rigel’s mission is to become a source of novel, small-molecule drugs to meet large, unmet medical needs. Rigel has identified three lead product development programs: mast cell inhibition to treat immunologic diseases such as asthma/allergy and autoimmune disorders, antiviral agents to treat hepatitis C, and ligases, a new class of cancer drug targets. Rigel has begun clinical testing of its first product candidate, R112, for allergic rhinitis, and it plans to begin clinical trials of three additional drug candidates, for the treatment of hepatitis C, rheumatoid arthritis and asthma, by the end of 2004.

This press release contains “forward-looking” statements, including statements related to the timing and subject matter of future clinical trials and the properties and potency of pre-clinical compounds such as R803. 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 “plans,” “believes,” “potential” and similar expressions are intended to identify these forward-looking statements. There are a number of important factors that could cause Rigel’s results and plans 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, as well as other risks, detailed from time to time in Rigel’s SEC reports, including its Quarterly Report on Form 10-Q for the quarter ended June 30, 2003 and Annual Report on Form 10-K, as amended, for the year ended December 31, 2002. Rigel does not undertake any obligation to update forward-looking statements.

1. Alter, M.J. et al. The Prevalence of Hepatitis C Virus Infection in the United States, 1988 through 1994 New England Journal of Medicine 341(8):556-62, 1999

Rigel Contact: Raul Rodriguez (1-650-624-1302)