Safety and Efficacy of Damoctocog Alfa Pegol in Previously Treated Children Aged 7 to < 12 Years With Severe Haemophilia A in the Phase 3, Open Label Alfa‐PROTECT Main Study

BACKGROUND: In the earlier PROTECT VIII Kids study (NCT01775618), damoctocog alfa pegol was efficacious for prevention and treatment of bleeds in children aged < 12 years with severe haemophilia A. OBJECTIVE: Assess the safety of damoctocog alfa pegol, including hypersensitivity and loss of efficacy (LoE) due to an immune response to polyethylene glycol, in children aged 7 to < 12 years with severe haemophilia A. METHODS: Alfa-PROTECT is a phase 3, multicentre, open-label, single-arm study (NCT05147662). Primary endpoint was the incidence of adverse events of special interest (AESI) leading to discontinuation during the first 4 exposure days. RESULTS: Overall, 35 children enrolled; 32 completed the 6-month study, 21 (60%) reported ≥ 1 AE. Median (range) treatment duration was 182 (172-198) days. All AEs were mild/moderate; 3/35 children (8.6%) had study drug-related AEs. One (2.9%) LoE event was considered an AESI, and led to temporary treatment interruption. No AEs resulted in study drug discontinuation. The probability of < 5% of patients experiencing an AESI was 92.2%. Bleed protection was maintained with damoctocog alfa pegol prophylaxis. CONCLUSIONS: These data confirm the safety profile of damoctocog alfa pegol in children aged 7 to < 12 years with severe haemophilia A. Secondary endpoints indicate treatment was efficacious. TRIAL REGISTRATION: The Alfa-PROTECT trial is registered at ClinicalTrial.gov (NCT05147662).