AstraZeneca presents mixed data on fostamatinib in RA

Shares of Anglo-Swedish drug major AstraZeneca (LSE: AZN) fell 2.1% to $47.88 in premarket US trading yesterday, after the company announced mixed top-line results of OSKIRA-4, a Phase IIb monotherapy study of fostamatinib, the first kinase inhibitor with selectivity for SYK (spleen tyrosine kinase) in development as an oral treatment for rheumatoid arthritis (RA). Its partner, Rigel Pharmaceuticals’ (Nasdaq: RIGL), slumped 25.9% to $6.25 on the news.

Results from the Phase IIb trial confirm the efficacy signal for the product but failure to show it can match Abbott Lab’s Humira (adalimumab)’s efficacy are likely to limit the product’s commercial potential. Nonetheless, say analysts at Panmure Gordon, “Phase II trials are designed to provide direction for the Phase III program and to that end we are making no changes to forecasts, nor do we expect consensus to change dramatically.”

Study details