Interim results from the phase 3b HAVEN 7 trial suggest that emicizumab is a safe and efficacious option for infants with severe hemophilia A without factor VIII inhibitors, according to data presented at the 2022 ASH Annual Meeting.

“This study of emicizumab prophylaxis in this population was requested by the community,” Steven W. Pipe, MD, of the University of Michigan, said when presenting the study. Emicizumab is currently approved for prophylaxis in infants, but questions about its efficacy and tolerability remain.

The multicenter, open-label, phase 3b HAVEN 7 trial treated 54 infants aged less than 1 year with severe hemophilia A with subcutaneous emicizumab.  The emicizumab dose for the initial 4 weeks was 3 mg/kg administered weekly, followed by 3 mg/kg every 2 weeks for 52 weeks. At 53 weeks, patients could continue with the same dosing or switch to 1.5 mg/kg weekly or 6 mg/kg every 4 weeks. The endpoints included number of treated bleeds, all bleeds, treated spontaneous bleeds, and treated joint bleeds.

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At baseline, the median age was 5.1 months and 74.1% of patients had a family history of hemophilia. There were 44.4% of patients who were previously untreated and a total of 66.7% of patients had experienced at least 1 bleed prior to receiving their first dose of emicizumab.

“Questions from the community in this population included whether efficacious plasma levels of emicizumab could be achieved in the youngest infants,” Dr Pipe said in his presentation. After the loading dose, the mean trough concentration was 63.2 μg/mL and steady-state concentrations were 60 to 65 μg/mL. The steady-state concentrations increased with age and plateaued at 6 months at approximately 65 μg/mL.

There were 42.6% of patients who did not experience any bleeds and 77.8% who did not develop any bleeds that required treatment. No patients required treatment for spontaneous bleeds and 98.1% had no treated muscle bleeds.

The modeled annual bleed rate was 0.4 for all treated bleeds, 1.9 for treated joint bleeds, and 0 for treated muscle bleeds. The ABR for treated spontaneous bleeds was not estimable.

There were no new safety signals and AEs did not cause study withdrawal or dose modifications or interruptions. Treated-related adverse events (TRAEs) developed among 16.7% of patients. None of the patients experienced a thromboembolic event, thrombotic microangiopathy, or systemic hypersensitivity, anaphylaxis, or an anaphylactoid reaction. None of the evaluable patients demonstrated anti-drug antibodies.

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

Disclosures: This study was supported by F. Hoffmann-La Roche Ltd. Please see the original reference for a full list of disclosures.


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. Presented at ASH 2022. December 10-13, 2022. Abstract 187.