Emicizumab Prophylaxis Efficacious and Well-Tolerated in Infants with Severe Hemophilia A Without Inhibitors

Due to challenges with intravenous factor VIII administration, many infants with severe hemophilia A do not receive prophylaxis until 1 year of age or older. Emicizumab (HEMLIBRA) can be administered subcutaneously following initial hemophilia A diagnosis, which may reduce risk of spontaneous and traumatic bleeds, importantly including intracranial hemorrhage. The Phase IIIb multicenter, open-label HAVEN 7 study evaluated the efficacy, safety and pharmacokinetics of emicizumab in infants 12 months of age or younger with severe hemophilia A without factor VIII inhibitors.

The median age of the 55 male study participants was 4 months. All received emicizumab for at least 52 weeks, with a median treatment duration of 100.3 weeks (range 52-18 weeks). Of a total of 207 bleeds (treated or untreated) reported in 46 participants (83.6%), 42 treated bleeds — all traumatic — were reported in 25 participants (45.5%). The annualized treated bleeding rate was 0.4 bleeds (95% confidence interval, 0.30-0.63 bleeds). Thirty infants (54.5%) experienced no treated bleeds, 52 infants (94.5%) had no treated joint bleeds and all 55 infants (100%) had no treated spontaneous bleeds.

Nine of the 55 participants had one or more emicizumab-related adverse events, all of which were grade 1 injection-site reactions. No adverse event led to treatment changes or withdrawal. Sixteen participants reported 30 serious adverse events, none of which were considered emicizumab-related. Pharmacokinetics profiles were similar to those in previous studies in adult populations treated with emicizumab.

“This primary analysis of HAVEN 7 confirms that emicizumab is efficacious and well-tolerated in infants with severe hemophilia A without factor VIII inhibitors,” the investigators concluded.