Rigel tanks as Phase III trial of fostamatinib in hemolytic anemia misses

Shares in US biotech Rigel Pharmaceuticals (Nasdaq: RIGL) plunged 60% to $0.70 on Wednesday, after the company reported that its oral SYK inhibitor Tavalisse (fostamatinib) missed the primary endpoint of the Phase III FORWARD trial in patients with warm autoimmune hemolytic anemia (wAIHA).

The trial did not demonstrate statistical significance in the primary efficacy endpoint of durable hemoglobin response in the overall study population.

In a post-hoc regional analysis of US, Canadian, Australian, and Western European trial sites, patients treated with fostamatinib had a favorable durable hemoglobin response compared to placebo, whereas in the Eastern European trial sites patients did not. Rigel plans to continue analyzing the data to understand the geographical differences in patient disease characteristics and outcomes and discuss these findings with the US Food and Drug Administration (FDA).