SOUTH SAN FRANCISCO, Calif., July 9 /PRNewswire-FirstCall/ -- Rigel Pharmaceuticals, Inc. (Nasdaq: RIGL - News) today announced that R788 (fostamatinib disodium) produced significant clinical improvement in rheumatoid arthritis (RA) patients in the recently completed TASKi2 Phase 2b clinical trial of 457 patients treated for up to 6 months. The groups treated with 100 mg of R788 bid (twice a day) and 150 mg qd (once a day) reported higher ACR 20, ACR 50, ACR 70 and DAS28 response rates than the placebo group. The efficacy results for the two dosing groups were comparable, although the response rates for the 100 mg bid group was uniformly greater. Consistent with the previous Phase 2a clinical trial (TASKi1), the onset of effect of R788 occurred within one week after the initiation of therapy and was maintained. The most frequent adverse events were expected based on TASKi1 and appear to be manageable. The significant, early and sustained efficacy, combined with a good safety profile, supports Rigel's plans to conduct corporate partnership discussions with respect to R788 and initiate a Phase 3 clinical program with R788 in RA in the first half of 2010 with a corporate partner.
"These are impressive results," said James M. Gower, chairman and chief executive officer of Rigel. "The data from this clinical trial and the soon to be completed TASKi3 clinical trial, a total of over 670 patients, will guide the design of the Phase 3 trials that we plan to launch with a corporate partner in the first half of next year," he added.
Efficacy Results
[See Release for Efficacy Results as these do not format well into this post]
Safety Results
The most common clinically meaningful drug-related adverse events noted in TASKi2 were diarrhea and hypertension. Dose reduction options were pre-specified in the trial protocol and in cases where doses were reduced, patients generally completed the clinical trial with minimal safety issues. The most common adverse events in the trial overall were related to infections, though these were generally evenly distributed among the placebo and active dose groups.
The mean increase in blood pressure from baseline at 6 months, using a last observation carry forward methodology, was less than 0.5 mmHg for the 150 mg qd dose group and approximately 1 mmHg for the 100 mg bid dose group. Approximately 18% and 23% of patients in the 150 mg qd and the 100 mg bid dose groups, respectively, had blood pressure medication adjusted or in some cases initiated during the course of the study, compared with 7% of the placebo patients. The blood pressure was successfully reduced in these patients, and their blood pressure was generally well controlled throughout the trial. The blood pressure medications were standard doses of common blood pressure medications such as ACE inhibitors or diuretics.
"R788 continues to perform with strong efficacy and good tolerability in the groups of patients with RA who have failed to respond to methotrexate," said Elliott Grossbard, M.D., chief medical officer for Rigel. "We now have a much better understanding of R788's safety profile and believe that the observed side effects may be effectively managed," he added. . . .
[See Release for "Safety Results," "Treatment Emergent Adverse Events," "Mean Blood Pressure," and "Mean Systolic BP if had Adjustment or Initiation of BP Medication" tables as they do not format well into this post] . . .
Study Design
TASKi2 was a 6 month, multi-center, randomized, double blind, placebo controlled, parallel dose clinical trial involving 457 RA patients in the U.S., Latin America and Europe who had failed to respond to methotrexate alone. The patients were randomly assigned to two cohorts and thus received R788 orally in either 100 mg bid (twice daily) or 150 mg qd (once daily) doses or placebo for a period of 6 months. Within in each cohort, patients were assigned on a 2:1 basis to R788 or placebo. All of the patients continued to receive their same stable dose of methotrexate throughout the clinical trial period.
Efficacy assessments for each participant were based on the American College of Rheumatology criteria, which denotes at least a 20% (ACR 20) improvement, at least a 50% (ACR 50) improvement, or at least a 70% (ACR 70) improvement, from the baseline assessment at the end of the 6 month treatment period. The ACR measurement factors include reported physician and patient global assessment of disease activity, patient reported pain score, and any change in C-reactive protein (CRP) in the patients' blood. The primary efficacy endpoint for the study was the percent of patients assigned to the R788 100 mg bid dose who were ACR 20 responders at the end of 6 months. Secondary efficacy endpoints included a comparison of response rates for the R788 100 mg bid and R788 150 mg qd doses at the ACR 20, ACR 50 and ACR 70 scores, as well as Disease Activity Scores (DAS) over the period of 6 months.
R788 and RA
RA is a progressive, painful and potentially debilitating disease, that affects more than 2 million people in the U.S. It is a chronic inflammatory disease that puts the body's immune system into overdrive where it ultimately causes inflammation in the joints and destroys soft tissues, cartilage and bone. Rigel's R788 is a novel, orally available syk kinase inhibitor designed to interrupt the cellular signaling at the trigger point of inflammation, thereby stopping the progression of the disease. . . .
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