Drug fails to meet endpoint in phase 3 ITP trial

The response rate is significantly better in the fostamatinib arm across all subgroups, regardless of whether patients had prior splenectomy, prior exposure to thrombopoietic agents, or baseline platelet counts above or below 15,000/uL.

In the combined dataset, patients who met the primary endpoint had their platelet counts increase from a median of 18,500/uL at baseline to more than 100,000/uL at week 24 of treatment.

In addition, patients who met the primary endpoint had a timely platelet response, and that response was enduring, according to James B. Bussel, MD, a professor at Weill Cornell Medicine in New York, New York, principal investigator on the FIT phase 3 program, and a member of Rigel’s advisory/scientific board.

“The FIT phase 3 studies have both demonstrated that fostamatinib provided a robust and enduring benefit for those patients who responded to the drug,” he said.

Safety

In FIT 1, the overall incidence of adverse events (AEs) was 96% in the fostamatinib arm and 76% in the placebo arm. The incidence of serious AEs was 16% and 20%, respectively. And the incidence of treatment-related AEs was 77% and 28%, respectively.

AEs (in the fostamatinib and placebo arms, respectively) included gastrointestinal complaints (nausea, diarrhea, vomiting, abdominal pain; 61% and 20%), nausea (29% and 4%), diarrhea (45% and 16%), infection (33% and 20%), hypertension during visit (35% and 8%), and transaminase elevation (22% and 0%).

In FIT 2, the overall incidence of AEs was 71% in the fostamatinib arm and 78% in the placebo arm. The incidence of serious AEs was 10% and 26%, respectively. And the incidence of treatment-related AEs was 39% and 26%, respectively.

AEs (in the fostamatinib and placebo arms, respectively) included gastrointestinal complaints (22% in both arms), nausea (8% and 13%), diarrhea (18% and 13%), infection (22% in both arms), hypertension during visit (20% and 17%), and transaminase elevation (6% and 0%).