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news.Rigel Pharmaceuticals has reported that its oral syk kinase inhibitor, R788 has demonstrated statistically significant results in treating rheumatoid arthritis patients in a recently completed Phase II clinical trial.
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Groups treated with R788 at 100mg and 150mg orally, twice daily, showed higher ACR20, ACR50, ACR70 and DAS28 response rates than the placebo group. The efficacy results for the 100mg and the 150mg dose groups were fairly comparable. Dramatically, the onset of the effect in these dose groups occurred as early as one week after initiation of therapy.
The clinical trial was a multi-center, randomized, double blind, placebo controlled, ascending dose study involving 189 patients in three approximately equal-size cohorts receiving 50, 100, or 150mg. Within each cohort, patients were assigned on a 3:1 basis to R788 or placebo.
The clinical trial was conducted over a 12-week treatment period in patients who had rheumatoid arthritis (RA) for at least 12 months. These patients had active disease despite receiving adequate stable doses of methotrexate over the preceding six months. All of the patients continued to receive their same stable dose of methotrexate throughout the clinical trial period and extension.
Efficacy assessments for each participant were based on the American College of Rheumatology criteria, which denote at least a 20% (ACR 20) improvement, at least a 50% (ACR 50) improvement, or at least 70% (ACR 70) improvement, from the baseline assessment at the end of the 12-week 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 who were ACR 20 responders at the end of week 12. Secondary efficacy endpoints were ACR 50 and ACR 70 scores as well as disease activity score at the end of week 12.
Elliott Grossbard, senior vice president of medical development at Rigel, said: “In this clinical trial both the 100mg and 150mg doses improved arthritis symptoms and did so quickly. We plan to initiate the next clinical trial with R788 in RA in 2008.”