Efanesoctocog Alfa Effective Bleeding Prophylaxis in Severe Pediatric Hemophilia A

In pediatric patients younger than 12 years who have severe hemophilia A, once-weekly prophylaxis with efanesoctocog alfa brings effective bleeding prevention with only mild adverse events. These were the findings of a phase III, open-label study recently published in the New England Journal of Medicine.

“Data on outcomes of efanesoctocog alfa treatment in children younger than 12 years of age with severe hemophilia A are limited,” the investigators wrote regarding the need for the study.

The study comprised 74 male pediatric patients with previously treated severe hemophilia aged younger than 12 years, 38 of whom were younger than six years and 36 aged six or older. For 52 weeks, the patients received once-weekly efanesoctocog alfa prophylaxis dosed at 50 IU per kilogram of body weight.

For the primary endpoint of the study, the patients were observed for the occurrence of neutralizing antibodies against factor VIII. None developed in the study cohort.

Seventy-three patients were treated according to the study protocol. The investigators calculated a median annualized bleeding rate of 0.00 and a model-based mean annualized bleeding rate of 0.61 for these patients.

Sixty-five of the treated patients had no spontaneous bleeding episodes, 47 had no treated bleeding episodes, and 61 had no episodes of bleeding into joints. Of 43 bleeding episodes, 41 were resolved using a single injection of efanesoctocog alfa.

The investigators calculated that with the once-weekly interventions received by the cohort, the mean factor VIII activity at a steady state in the patients stayed greater than 40 IU per deciliter for three days after receiving the dose, and greater than 10 IU per deciliter for nearly seven days after the dose. They also calculated a geometric mean terminal half-life of 40 hours.

Regarding safety results, most adverse events were not serious, and the investigators did not report any of the serious adverse events as related to the study treatment.

The study was funded by Sanofi and Sobi.

Reference

Malec L, Peyvandi F, Chan AKC, et al. Efanesoctocog alfa prophylaxis for children with severe hemophilia A. N Engl J Med. 2024;391(3):235-246. doi:10.1056/NEJMoa2312611