FDA Grants Priority Review to Emicizumab-Kxwh for Hemophilia A

This morning, Genentech announced that the US Food and Drug Administration (FDA) has accepted the company’s supplemental Biologics License Application (sBLA) and granted Priority Review to its product, emicizumab-kxwh (HEMLIBRA), for the treatment of hemophilia A without factor VIII inhibitors in both children and adults.

The sBLA was grounded on data from the phase 3 HAVEN 3 study, which assessed the safety, efficacy, and dosage of emicizumab-kxwh. The phase 3 HAVEN 3 assessed the administration of (emicizumab) prophylaxis every week or every 2 weeks in individuals with hemophilia A without factor VIII inhibitors.

Emicizumab prophylaxis is a bispecific factor IXa- and factor X-directed antibody engineered to join factor IXa and factor X, which are necessary proteins in the activation of natural coagulation cascade and restoration of the blood clotting process for individuals with hemophilia A. It is a prophylactic treatment that can be given once weekly by an injection of a ready-to-use solution under the skin.

In the phase 3 HAVEN 3 study, adults and adolescents aged 12 years or older without factor VIII inhibitors who received emicizumab prophylaxis every week or every 2 weeks respectively showed a 96% (p<0.0001) and 97% (p<0.0001) reduction in treated bleeds compared to those who received no prophylaxis.

To allow for an intra-patient comparison of 2 prophylaxis regimens, individuals who had previously received factor VIII prophylaxis in a non-interventional study switched to emicizumab-kxwh prophylaxis in an additional arm of the study. In this intra-patient comparison, it was observed that emicizumab-kxwh showed a statistically significant reduction of 68% (p<0.0001) in treated bleeds, making it the first medicine to show superior efficacy to prior treatment with factor VIII prophylaxis, which is the standard of care.

Additionally, no unexpected or serious adverse events (AEs) related to emicizumab-kxwh in the HAVEN 3 study occurred, and the most common AEs were correlative with previous studies. Injection site reactions, joint pain (arthralgia), common cold symptoms (nasopharyngitis), headache, upper respiratory tract infection, and influenza included the most common AEs observed in 5% or more of the study’s participants.

Previously, the FDA approved emicizumab-kxwh in November 2017 for routine prophylaxis to prevent or reduce the frequency of bleeding instances in adults and children with hemophilia A with factor VIII inhibitors based on results from the HAVEN 1 and HAVEN 2 studies. The FDA is anticipated to decide on approval by October 4, 2018.

Globally, regulatory authorities in other countries around the world, including the European Commission in February 2018, recently approved emicizumab-kxwh for routine prophylaxis of bleeding episodes in those with hemophilia A with factor VIII inhibitors.

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