Phase 2 Results of Rigel Pharmaceuticals, Inc.'s R788 Show Clinical Benefit in Diffuse Large B-Cell Lymphoma and CLL Results To Be Presented Today at American Society of Hematology Meeting in San Francisco

SAN FRANCISCO, Dec. 7 /PRNewswire-FirstCall/ -- Results of the Phase 2 clinical trial of R788 (fostamatinib disodium) in patients with relapsed or refractory B-Cell non-Hodgkin's lymphoma (NHL) will be presented today at a plenary session during the 50th Annual American Society of Hematology (ASH) Meeting. The results affirm preliminary reports that Rigel's oral Syk inhibitor is well-tolerated by these patients and shows therapeutic benefit in patients suffering from diffuse large B-Cell lymphoma (DLBCL) and chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL).

Rigel will host a conference call today at 4:00 p.m. PST to discuss these results (see conference call details below).

"Despite the fact that the patients enrolled in this trial had advanced disease and had failed treatment with marketed therapies, a significant number of them were particularly responsive to Syk inhibition with R788," said Jonathan Friedberg, M.D., M.S.Sc., Associate Professor of Medicine, James P. Wilmot Cancer Center, University of Rochester and lead investigator for the clinical trial. "I am encouraged by this data and look forward to conducting additional trials of R788, particularly in patients with DLBCL and CLL/SLL types of non-Hodgkin's lymphomas," he added.

Clinical Trial Design

This clinical trial was conducted in two Phases. Phase 1 included a small group of patients and resulted in the selection of the dosing regimen employed in Phase 2. Nearly equal numbers of patients were enrolled in the three Phase 2 groups that included, respectively: DLBCL, follicular lymphoma (FL) and other non-Hodgkin's lymphomas (specifically CLL/SLL, MCL, MALT, marginal zone, and lymphoplasmacytic). Prior to enrollment in the R788 trial, all patients enrolled in the clinical trial had received various standard-of-care treatments for their disease, including combination chemotherapy, and had failed to respond to those therapies or suffered a relapse of the disease. A total of 68 patients received 200 mg PO bid (orally, twice daily) of R788 until disease progression occurred. Response to treatment was evaluated using standard NHL response criteria (The Cheson Criteria). Treatment-related adverse events included cytopenias, fatigue, diarrhea/abdominal discomfort and hypertension. Most adverse events were mild to moderate and were reversible. Four patients are continuing to receive R788, including 2 from the CLL/SLL group and 1 from the DLBCL group.

B-Cell Lymphoma and Syk Inhibition

Lymphoma affects an estimated 500,000 people in the United States, with 332,000 of them suffering from non-Hodgkin's lymphoma. Diffuse large B-cell lymphoma is the most common type of NHL and is generally categorized as aggressive, marked by rapidly growing tumors in the lymph nodes, spleen, liver, bone marrow and other organs. A variety of treatment options for NHL exist, including chemotherapy and radiation, but the five-year survival rate for NHL patients is estimated to be around 50%. Even for those who respond to treatment, recurrence of the disease is common.

A growing field of research on the cellular signaling associated with these lymphomas indicates that inhibiting Syk (spleen tyrosine kinase) in aberrant cells may control spread of the disease. Two additional research studies on the topic are also being presented at the ASH meeting. They are: Abstract 377, entitled "BCR, Signaling Diversity in Human Lymphoma B Cells Correlates with Follicular Lymphoma Patient Clinical Outcomes" and Abstract 802, entitled "BCL-6 Regulates Tonic BCR Signaling in Diffuse Large B-Cell Lymphomas." Further information on R788 in B-cell lymphoma is available at Rigel's website: http://www.rigel.com/rigel/lymphoma.

Conference Call and Webcast Information

To access the live call, please dial 800-561-2693 (domestic) or 617-614-3523 (international) 10 minutes prior to the start time and use the passcode 36883961. A replay of the call will be available, in webcast and podcast formats, at approximately 6:00 p.m. PST on December 7, 2008 through December 14, 2008. To access the replay, please dial 888-286-8010 (domestic) or 617-801-6888 (international) and use the passcode 47095093. The conference call will also be webcast live and can be accessed from Rigel's website at http://www.rigel.com. Please connect to Rigel's website several minutes prior to the start of the live webcast to ensure adequate time for any software downloads that may be necessary.

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 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.

CONTACT: Raul Rodriguez of Rigel, +1-650-624-1302, rrodriguez@rigel.com;
or media, Susan C. Rogers of Alchemy Consulting, Inc., +1-650-430-3777,
susan@alchemyemail.com, for Rigel

Web site: http://www.rigel.com/