Emicizumab demonstrated efficacy and a favorable safety profile in a study of patients with non-severe hemophilia A without factor VIII (FVIII) inhibitors for whom prophylaxis was appropriate. The study was the phase 3 HAVEN 6 study, and results were published in Lancet Haematology.

The study investigators determined that the results were consistent with those of other HAVEN studies, demonstrating efficacy and favorable safety with emicizumab independently of the severity of the condition, prior therapy, or the dosing approach used. “Hence, emicizumab represents a valuable treatment option for people with non-severe haemophilia A without FVIII inhibitors warranting prophylaxis,” the investigators wrote in their report.

The multicenter, open-label study (ClinicalTrials.gov Identifier: NCT04158648) was conducted in Europe, North America, and South Africa and included patients with mild or moderate hemophilia without FVIII inhibitors requiring prophylaxis. Eligible participants also weighed 3 kg or more. Mild hemophilia was defined by having FVIII activity of >5% and <40%, and moderate hemophilia was defined by having FVIII activity of ≥1% to ≤5%.

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The study had a single treatment arm, which consisted of patients receiving subcutaneous emicizumab, dosed at 3 mg/kg and given once per week for 4 weeks. This was followed by a maintenance regimen chosen by the participant, with options of 1.5 mg/kg once per week, 3 mg/kg every 2 weeks, or 6 mg/kg given at 4-week intervals. The study had a primary objective of assessing multiple safety-related endpoints, and a primary efficacy endpoint of the annualized bleed rate for treated bleeds.

There were 73 patients assigned to treatment, of whom 72 received 1 or more doses of emicizumab. Most (71%) had moderate hemophilia A. Patients had a median age of 23.5 years (interquartile range [IQR], 12.0-36.0). The study had a median follow-up time of 55.6 weeks (IQR, 52.3-61.6). At baseline, approximately half (51%) of the study population had been receiving FVIII prophylaxis, and 33% of patients presented with target joints.

The median study follow-up duration was 55.6 weeks. The annualized bleed rate for treated bleeds in this study was 0.9 (95% CI, 0.55-1.52). Among participants, 67% did not have treated bleeds. The all-bleed annualized bleed rate was 2.3 (95% CI, 1.67-3.12). In the 24 weeks prior to study entry, the all-bleed annualized bleed rate had been estimated to be 10.1 (95% CI, 6.93-14.76).

One or more adverse events (AEs) were reported in 83% of participants, with the most common AEs being headache (17%), injection-site reaction (17%), and arthralgia (15%). One or more emicizumab-related AEs were reported in 21%, and no AEs resulted in withdrawal, modification, or interruption of treatment. There were serious AEs in 11% of patients, but none were considered emicizumab related. No deaths or thrombotic microangiopathies occurred.

“HAVEN 6 is the first phase 3 study to evaluate long-term prophylaxis specifically in people with non-severe haemophilia A, the results of which demonstrate the favourable benefit–risk profile of emicizumab in people with moderate or mild haemophilia A without FVIII inhibitors who warrant prophylaxis,” the study investigators wrote in their report.

Disclosures: The HAVEN 6 study was sponsored by Hoffmann-La Roche. Please refer to the original study for a full list of disclosures.


Négrier C, Mahlangu J, Lehle M, et al. Emicizumab in people with moderate or mild haemophilia A (HAVEN 6): a multicentre, open-label, single-arm, phase 3 study. Lancet Haematol. Published online January 27, 2023. doi:10.1016/S2352-3026(22)00377-5