Rigel Announces Presentations at the 2007 American Society of Hematology (ASH) Meeting

SOUTH SAN FRANCISCO, Calif., Dec. 5 /PRNewswire-FirstCall/ -- Rigel Pharmaceuticals, Inc. (Nasdaq: RIGL) today announced a number of presentations being given on Rigel product candidates at the upcoming American Society of Hematology Meeting and Exposition, at the Georgia World Congress Center in Atlanta, Georgia, December 8-11, 2007.

    Rigel Poster Presentations

    R935788: A phase 2, single center, open label, efficacy and safety,
             ascending dose, pilot study for the treatment of adult Immune
             Thrombocytopenic Purpura (ITP)
    Saturday, December 8, 2007  5:30 p.m. - 7:30 p.m.
    Session Name -- ITP, TTP and HIT
    Poster #464

    Targeting myeloproliferative diseases with JAK2 inhibitors
    Monday, December 10, 2007  5:00 p.m. - 7:00 p.m.
    Session Name -- Myeloproliferative Syndromes: Therapy
    Poster #769

    Merck Serono Poster Presentation on Rigel's R763/AS703569

    The novel aurora kinase inhibitor AS703569 shows potent anti-tumor
    activity in Acute Myeloid Leukemia (AML)
    Saturday, December 8, 2007  5:30 p.m. - 7:30 p.m.
    Session Name - Acute Myeloid Leukemias: Therapy, excluding Transplantation
    Poster #69

    Other collaboration presentations with Rigel product candidates

    Syk kinase inhibition by R406 inhibits BCR mediated B cell proliferation
    and interferes with BCR signal transduction in primary tumor samples
    Oral Presentation -- Tuesday, December 11, 2007  8:15 a.m.
    Session Name -- Lymphoma: Pre-Clinical Chemotherapy and Biologic Agents --
    Novel Agents, including Small Molecule Inhibitors

    Mechanistic paradigm for combination signal transduction inhibitor therapy
    in Zap70+ CLL involves bicompartmental functions of EZH2
    Monday, December 10, 2007  5:00 p.m. - 7:00 p.m.
    Session Name -- CLL: Clinical Biology
    Poster #318

    Constitutive activation of the protein tyrosine kinase syk in chronic
    lymphocytic leukemia B cells
    Saturday, December 8, 2007  5:30 p.m. - 7:30 p.m.
    Session Name -- CLL: Molecular Biology
    Poster #277

About Rigel (http://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 potential efficacy of Rigel's 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," "goal" 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, as well as other risks detailed from time to time in Rigel's SEC reports, including its Form 10-Q for the quarter ended September 30, 2007. Rigel does not undertake any obligation to update forward-looking statements.

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

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

SOURCE Rigel Pharmaceuticals, Inc.