Rigel Pharmaceuticals (RIGL) and AstraZeneca (AZN) announced the topline results from OSKIRA-2 and OSKIRA-3, the remaining pivotal Phase 3 clinical trials investigating fostamatinib, the first oral spleen tyrosine kinase, or SYK, inhibitor in development for rheumatoid arthritis, or RA. In the OSKIRA-2 study of patients inadequately responding to disease modifying anti-rheumatic drugs, or DMARDs, fostamatinib in combination with DMARDs showed statistically significant improvements in ACR20 response rates at 24 weeks in both the 100 mg twice daily (bid) group and the group receiving 100 mg bid for four weeks followed by 150 mg once daily compared to placebo. In the OSKIRA-3 study of patients inadequately responding to methotrexate, or MTX, and a single TNF-alpha antagonist, fostamatinib in combination with MTX showed statistically significant improvements in ACR20 response rates at 24 weeks in the 100 mg bid group, but not in the group given 100 mg bid for four weeks followed by 150 mg qd compared to placebo. Fostamatinib continues to be well tolerated by patients. The safety findings in both the OSKIRA-2 and OSKIRA-3 studies were generally consistent with those observed in the prior OSKIRA-1 study as well as the TASKi Phase 2 program.