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Emicizumab Can Be Used Without FVIII Inhibitors in Infants With Severe Hemophilia

December 20, 2022

Mid-January 2023

Ruth Jessen Hickman, MD

Ruth Jessen Hickman, MD, is a freelance medical and science writer based in Bloomington, Indiana.

Results of an interim analysis of the HAVEN 7 study indicated that emicizumab is safe and effective in infants with severe hemophilia A without factor VIII (FVIII) inhibitors, according to results presented at the 64th ASH Annual Meeting and Exposition.1

In the phase III, multicenter, open-label HAVEN 7 trial, Steven W. Pipe, MD, of the University of Michigan in Ann Arbor, and colleagues studied the safety and effectiveness of subcutaneous emicizumab in infants 12 months of age or younger (median 4.5 months) with severe hemophilia A. At the interim analysis date, 54 participants had received at least one dose, and median treatment duration was 42.1 weeks. No patients received prophylactic FVIII during the study period.

Bleeding was experienced by 57.4% of patients in 77 bleeding events; of these, 88.3% were traumatic in nature. No patients had intracranial hemorrhage, but 14 bleeds in 12 participants required treatment, with no patient having more than two such bleeds. Of the participants, 77.8% had no bleeds that required treatment, and no patient had a spontaneous bleed that required treatment.

“Participants had low model-based annualized bleeding rates,” Dr. Pipe added. For treated bleeds, the calculated annualized bleeding rate was 0.4; for all bleeds it was 1.9.

No adverse event (AE) necessitated treatment cessation, and no new safety signals were identified. Of the 16.7% of patients who had emicizumab-related AEs, all were injection site reactions.

Effective mean trough concentration of the treatment was achieved and maintained through the study period, with most infants showing increasing concentrations until about six months of age, Dr. Pipe said. He added that these steady trough concentrations were slightly above those reported in infants in the HAVEN 2 and HAVEN 6 trials while still being well within the established drug safety window.2,3

Additional study results showed mean factor IX and factor X concentrations were not affected by treatment, and the activated partial thromboplastin time (aPTT) coagulation test normalized by week three in most participants.

“This interim analysis suggests that emicizumab is efficacious and well tolerated in infants with severe hemophilia A without FVIII inhibitors,” Dr. Pipe concluded.

Dr. Pipe and colleagues will compile their primary analyses when all participants have completed at least 52 weeks in the study, and they plan to follow the patients for an additional seven years.

“People may be disappointed that this study was not sufficiently statistically powered to definitively demonstrate that this intervention prevents all intracranial hemorrhage,” Dr. Pipe said. “But so far the data are suggesting that emicizumab can give sustained protection.”

Any conflicts of interest declared by the authors can be found in the original abstract.


  1. Pipe SW, Collins P, Dhalluin C, et al. Emicizumab prophylaxis for the treatment of infants with severe hemophilia A without factor VIII inhibitors: Results from the interim analysis of the HAVEN 7 study. Abstract #187. Presented at the 2022 American Society of Hematology Annual Meeting and Exposition; December 10, 2022; New Orleans, Louisiana.
  2. Young G, Liesner R, Chang T, et al. A multicenter, open-label phase 3 study of emicizumab prophylaxis in children with hemophilia A with inhibitors.Blood. 2019;134(24):2127-2138.
  3. Négrier C, Mahlangu J, Lehle M. Emicizumab prophylaxis in persons with mild or moderate hemophilia A: Results from the interim analysis of the HAVEN 6 study. Blood. 2021;138(Supplement 1):343.


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