Treatment of hemophilia A with a weekly dose of efanesoctocog alfa may provide superior bleeding prevention compared to factor VIII prophylaxis, as well as normal to near-normal factor VIII activity and improvements in physical health, pain, and joint health, according to an article recently published in The New England Journal of Medicine.

For the phase 3 study, the authors recruited patients with severe hemophilia A aged 12 years or older. The 133 patients in group A received once-weekly prophylaxis with efanesoctocog alfa for 52 weeks, while the 26 patients in group B received on-demand efanesoctocog alfa treatment for 26 weeks, followed by once-weekly prophylaxis with the medication for 26 weeks.

The researchers measured the mean annualized bleeding rate in group A and performed an intrapatient comparison of the annualized bleeding rate during prophylaxis in group A with the rate during factor VIII prophylaxis before the study. Moreover, they evaluated the effectiveness of efanesoctocog alfa for the treatment of bleeding episodes, safety, pharmacokinetics, and changes in physical health, pain, and joint health.

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The median annualized bleeding rate of group A patients was 0, and the estimated mean annualized bleeding rate was 0.71. The mean annualized bleeding rate decreased from 2.96 before the study to 0.69, showing the superiority of efanesoctocog alfa prophylaxis over prestudy factor VIII prophylaxis. Group A patients also experienced improvements in their physical health, pain intensity, and joint health.

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In addition, 1 injection of efanesoctocog alfa was able to stop nearly all bleeding episodes in the overall study population. Weekly prophylaxis with the medication provided mean factor VIII activity of more than 40 IU/dL for nearly a week and 15 IU/dL at day 7.

There were no reports of severe adverse events associated with efanesoctocog alfa and the development of factor VIII inhibitors was not detected.

“In addition to maintaining high sustained factor VIII levels, uncoupling recombinant factor VIII from von Willebrand factor may also reduce interpatient pharmacokinetic variability of efanesoctocog alfa and increase the predictability of the factor VIII profile over time, because circulating von Willebrand factor levels vary widely among patients and within the same person,” von Drygalski and colleagues wrote.

Despite factor VIII prophylaxis as a standard treatment for hemophilia A, patients still experience life-threatening bleeding and bleeding into joints, which contributes to substantial morbidity as a result of chronic pain and hemophilic arthropathy.


von Drygalski A, Chowdary P, Kulkarni R, et al. Efanesoctocog alfa prophylaxis for patients with severe hemophilia A. N Engl J Med. Published online January 26, 2023. doi:10.1056/NEJMoa2209226