Rigel Pharmaceuticals (RIGL) announced results from a Phase 3 clinical trial, Study 047, evaluating lead product candidate fostamatinib for the treatment of immune thrombocytopenia (ITP), a bleeding disorder resulting from a person's immune system destroying blood platelets. The primary endpoint was stable platelet count defined as platelet counts of at least 50K/uL on at least four of six visits between Weeks 14 and 24. All had chronic/persistent ITP (platelet levels < 30K platelets/uL) and had received prior treatment. 18% (n=9/51) achieved the primary endpoint compared to 0% for placebo, a statistically valid result.