press release archive

Rigel Granted Key Patents in Immunology, Virology and Oncology

--29 Patents Issued in Past 24 Months--

SOUTH SAN FRANCISCO, Calif. - March 21, 2006

“Rigel remains on the forefront of ligase research, and has significant research and development expertise in immunology, virology and oncology where we have been identifying and developing novel, small-molecule drugs,” said Donald G. Payan, M.D., executive vice president and chief scientific officer of Rigel. “The large number of patents we have received over the past year exemplifies our productivity in these key disease areas.”

Of particular interest are several broadly enabling patent estates that have been issued to Rigel and cover key areas of drug discovery. These include:

Ligase
Rigel’s ligase patent estate includes five issued patents and one allowed patent in the United States.  The patents cover methods for identifying and/or measuring ubiquitin ligase activity in any disease state and screening for agents that modulate their activity using any of the major enzymes in the ligase pathway as well as particular enzymes. This means the patented subject matter covers screens using any ubiquitin activating enzyme (E1), any ubiquitin conjugating enzyme (E2) or any ligase (E3) as the drug target. Rigel has had two major collaborations based on these proprietary screens. 

IRES
Rigel has several issued patents covering screening for antiviral agents where IRES (internal ribozyme entry site) is the drug target. The IRES controls viral translation and protein synthesis, making it an important drug target. 

FACS
Rigel’s FACS patent estate covers patents issued in both the U.S. and Europe. FACS assays are used to investigate gene expression and characterize a given drug’s impact on diseased or healthy cells, and are capable of measuring multiple parameters at one time. Rigel’s patents cover FACS assays that measure a minimum of three parameters, which affect different disease states such as cancer and allergy-related disorders, and the cells’ response to drugs.

Rigel is pursuing opportunities to license these patent(s) to potential partners that are working in these areas. For more information please contact Rigel’s Business Development and Licensing Department at: BusDev@rigel.com or 650-624-1142.

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 diseases, cancer and viral diseases. Our goal is to move one new product candidate for a significant indication into the clinic each year. We have achieved this goal 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. We have product development programs in inflammatory/autoimmune diseases such as rheumatoid arthritis, thrombocytopenia, and asthma and allergy, as well as in cancer.

This press release contains "forward-looking" statements, including statements related to the potential value of Rigel’s patent portfolio or its development programs, Rigel's plans to pursue clinical development of product candidates and the timing thereof and the potential efficacy and safety of product candidates. 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," "intends," "expects," “believes,” 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 pre-clinical studies and clinical trials, as well as other risks detailed from time to time in Rigel's SEC reports, including its Annual Report on Form 10-K for the year ended December 31, 2005. Rigel does not undertake any obligation to update forward-looking statements.

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

Media Contact: Carolyn Bumgardner Wang, WeissComm Partners, Inc.
Phone: 415.946.1065
Email: carolyn@weisscommpartners.com