AstraZeneca returns fostamatinib program rights to Rigel

Anglo-Swedish drug major AstraZeneca (LSE: AZN) and US partner Rigel Pharmaceuticals (Nasdaq: RIGL) today (June 4) announced mixed top-line results from OSKIRA-2 and OSKIRA-3, the remaining pivotal Phase III clinical trials investigating fostamatinib, the first oral spleen tyrosine kinase (SYK) inhibitor in development for rheumatoid arthritis (RA).

In the OSKIRA-2 study of patients inadequately responding to disease modifying anti-rheumatic drugs (DMARDs), fostamatinib in combination with DMARDs showed statistically significant improvements in ACR20 response rates at 24 weeks in both the 100mg twice daily (bid) group and the group receiving 100mg bid for four weeks followed by 150mg once daily (qd) compared to placebo.

In the OSKIRA-3 study of patients inadequately responding to methotrexate (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 100mg bid group, but not in the group given 100mg bid for four weeks followed by 150mg qd compared to placebo.