Rigel Pharmaceuticals $RIGL nosedived more than 25% amid heavy trading volume in response to its announcement of failed results in the second of two Phase 3 study evaluating fostamatinib for the treatment of adult patients with chronic/persistent immune thrombocytopenia (low blood platelets). The trial, FIT 2 (Study 048), was unsuccessful in achieving its primary endpoint of a statistically valid response rate compared to placebo.