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Initiated in January 2007, the study evaluated the safety and efficacy ofR788 in adult ITP patients who had previously undergone and failed to respondto available treatments. Despite the severity of their disease, a majority ofthe patients responded favorably to the study drug. The primary side effectswere gastrointestinal related events in certain patients.
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"The effects of R788 treatment in this very refractory group of ITPpatients are impressive. The majority of these patients have reportedimportant clinical benefit from R788, and I look forward to further studieswith this exciting agent," said James B. Bussel, M.D., director of thePlatelet Research and Treatment program at the Phyllis and David KomanskyCenter for Children's Health and NewYork-Presbyterian Hospital/Weill CornellMedical Center and professor of pediatrics in obstetrics and gynecology and inmedicine at the Weill Cornell Medical College, and principal investigator onthis study.
Elliott Grossbard, M.D., senior vice president of medical development atRigel, said, "We are pleased with the results of this Phase 2 study of R788and have already begun to review the data to determine the appropriate nextsteps." He added, "Rigel's oral R788 drug candidate may not only help patientswith ITP, but may also have potential therapeutic benefit in patients withrheumatoid arthritis and lymphoma, where we have additional Phase 2 studiesongoing."
Study Design and Results
This single-center, ascending dose, proof-of-concept study evaluatedvarious doses of R788 with most patients receiving between 100 to 175 mg/dayBID. The study enrolled adult patients in the U.S. who have chronic refractoryITP. The patients were monitored for safety and early efficacy, with theprimary efficacy marker being the measure of platelet counts compared to eachpatient's baseline measurement taken prior to introduction of R788.
Nine of the first 14 patients (64%) studied responded favorably to R788treatment with higher stable platelet counts; six of these had peak plateletcounts of greater than 100,000 platelets/ul of blood. Two patients, who hadpreviously failed a wide range of other treatments and were receiving weeklyIV gammaglobulin, maintained platelet counts while on only R788 for 20 weeksof the study. For those two patients, this marked the first time in 10 yearsthat each achieved prolonged avoidance of intravenous immunoglobulin Ginjections. Overall these patients were highly refractory with most havingfailed several other therapies, 10 had failed splenectomy and 5 were over 70years old. The primary side effects were GI-related symptoms. R788 elevatedblood pressure in some patients but appeared not to have significant effect onneutrophil counts.
An abstract of these results is available on the American Society ofHematology (ASH) website. A more complete and updated poster presentation willbe made at the ASH meeting on December 8, 2007, from 9:00a.m. - 7:30p.m., inAtlanta, GA.
Immune Thrombocytopenic Purpura
ITP affects approximately 200,000 people in the U.S., with an estimated30,000 new cases each year. In patients with ITP, the immune system attacksand destroys the body's own blood platelets, which play an active role inblood clotting and healing. ITP patients can suffer extraordinary bruising,bleeding and fatigue as a result of low platelet counts. Failure offirst-line medical therapy for ITP, which is primarily steroids, c
