press release archive

Rigel Discusses Two Lead Product Candidates at UBS Warburg Conference

New York, NY - October 11, 2001

Rigel Pharmaceuticals, Inc. (Nasdaq: RIGL) discussed pre-clinical data and strategy for its lead product candidates in asthma and oncology at the UBS Warburg Global Life Sciences Conference in New York.

The data was presented by Rigel's Chief Financial and Operating Officer, Brian C. Cunningham, as part of a presentation updating the company's operational progress. Rigel’s Mast Cell Asthma program seeks to block three mast cell activation pathways: degranulation, leukotriene release and cytokine production. To date, the lead compound has succeeded in key in vivo animal models used to test efficacy for asthma compounds.

In the oncology area, Rigel reviewed pre-clinical data from studies involving the company's small molecule ubiquitin ligase inhibitors which reduce tumor volume in animal studies of colon and non-small cell lung cancers. Ubiquitin ligases are enzymes involved in many important cellular functions, including cell division and the progression of certain cancers. These enzymes represent a promising new class of anti-cancer targets, and Rigel is developing inhibitors to work selectively against these targets at the molecular level.

"We are very proud of this pre-clinical data as we believe it is a successful demonstration of how Rigel is integrating its target discovery and validation technology with its expanding chemistry and pre-clinical platforms with this very important new class of targets,” said Mr. Cunningham. "Based on this data as well as other studies, we plan to select a clinical candidate next year."

Ubiquitin Ligases and Rigel

Ubiquitin ligases are a very large family of enzymes found in all mammalian cells that can selectively tag proteins for destruction. While ubiquitin ligases have been implicated in many diseases, their role in cancer and inflammation is currently the best understood. In some types of cancer, for example, ubiquitin ligases tag for destruction "healthy proteins" that help direct a cell to grow and divide normally. Without these healthy, regulating proteins in place, abnormal cell division and proliferation can occur, causing the cell to become cancerous. The goal of Rigel's oncology-focused program is to inhibit the ability of ubiquitin ligases to tag these "normal" proteins for destruction.

Rigel has significant expertise in the area of ubiquitin ligases, with programs underway in the areas of cancer and inflammation, and is a leader in the development of small molecule (orally-available) inhibitors of these enzymes. The company has built a strong infrastructure in this area and has over 30 people working in the areas of biology, proteomics, high-throughput screening, bioinformatics and chemistry, and has generated many promising initial chemical hits. In addition, an experienced preclinical oncology development team is in place to optimize these leads and take them into the clinic.

Moreover, the company has assembled a strong intellectual property position in this area to protect its many novel discoveries and is collaborating with companies that can help accelerate the progress of the ubiquitin ligase program. In fact, in the last month alone, Rigel announced two new collaborations for its oncology ubiquitin ligase program: one with MediChem Life Sciences of Chicago to express, purify and co-crystallize important protein complexes, and another with Evotec OAI of Hamburg, Germany, for medicinal chemistry services to optimize Rigel's small molecule ubiquitin ligase compounds so that they contain desirable pharmaceutical properties.

Rigel Pharmaceuticals is a drug discovery and development company that uses advanced functional genomics tools to discover novel drug targets. Rigel's technology is designed to identify molecules which play an important role in regulating a human cell's response to disease by testing a very large number of proteins in a very large number of cells to determine which proteins will change the cell's response to the disease. Rigel currently has programs in asthma/allergy, autoimmunity, transplant rejection, rheumatoid arthritis, inflammatory bowel disease, chronic bronchitis, cancerous tumor growth and hepatitis C. Rigel has multi-year collaborations with Pfizer Inc., Cell Genesys, Inc., Janssen Pharmaceutica N.V. and Novartis Pharma A.G. Rigel is based in South San Francisco, California.

Statements included in this press release that are not historical in nature are "forward-looking statements" within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. These statements include those regarding the potential direction and applicability of Rigel’s research and development efforts and the timing and success of any future clinical trials. Rigel cautions readers that forward-looking statements are subject to certain risks and uncertainties that could cause actual results to differ materially from those indicated in the forward-looking statements due to the risks and factors identified in Rigel's Annual Report on Form 10-K for the year ended December 31, 2000 and other filings made with the Securities and Exchange Commission from time to time. The information in this press release is current as of its release date. Rigel does not intend to update the forward-looking information contained in this press release.