Rigel dips on fostamatinib Phase III ITP miss

Rigel Pharmaceuticals Inc. (NASDAQ:RIGL) dropped $0.49 (15%) to $2.73 on Thursday after fostamatinib disodium (formerly R788) missed the primary endpoint of the FIT 2 trial, the second of two Phase III studies of the candidate to treat idiopathic thrombocytopenic purpura. Fostamatinib failed to significantly improve stable platelet response rates vs. placebo, as defined by platelet counts of at least 50,000/uL of blood on at least four of the last six qualifying blood draws.

In the 74-patient study, fostamatinib led to a response rate of 18% vs. 4% for placebo (p=0.152). Rigel attributed the miss to a single placebo responder. ...