The Food and Drug Administration (FDA) has accepted and granted Priority Review to the Biologics License Application (BLA) of emicizumab (Genentech) for the prophylactic treatment of hemophilia A with factor VIII inhibitors in adults, adolescents and children.

The BLA submission was supported by data from two Phase 3 studies, HAVEN 1 and HAVEN 2. HAVEN 1 was a randomized, multicenter, open-label trial evaluating the efficacy, safety and pharmacokinetics of emicizumab prophylaxis compared to on-demand bypassing agents (BPAs) [no prophylaxis; episodic use only] in adults and adolescents ≥12yrs old. The study met its primary endpoint, showing that prophylaxis with emicizumab demonstrated a clinically meaningful and statistically significant reduction in treated bleeds of 87% (risk rate [RR]=0.13, P<0.0001) compared to on-demand BPAs. Detailed results from HAVEN 1 were published in The New England Journal of Medicine.

HAVEN 2 is a single-arm, multicenter, open-label trial evaluating the efficacy, safety and pharmacokinetics of once-weekly SC emicizumab in children <12yrs. Interim results from the study were consistent with the positive results from HAVEN 1. Results from both studies were presented at the 26th International Society on Thrombosis and Haemostasis (ISTH) Congress in July 2017. Additional studies for emicizumab in hemophilia A with and without inhibitors are ongoing. 

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A Prescription Drug User Fee Act (PDUFA) action date of February 23, 2018 has been set by the FDA to make a decision on approval. The FDA previously granted emicizumab Breakthrough Therapy designation for hemophilia A in adults and adolescents with inhibitors.

Emicizumab, a once weekly, ready-to-use solution for SC injection, is an investigational bispecific monoclonal antibody designed to bring together factors IXa and X, proteins required to activate the natural coagulation cascade and restore the blood clotting process.

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