Background: Haemophilia A management has advanced significantly with the introduction of extended half-life (EHL) recombinant factor VIII (FVIII) therapies, notably efmoroctocog alfa. Efanesoctocog alfa further extends FVIII half-life by decoupling it from the von Willebrand Factor, allowing once-weekly dosing with sustained FVIII activity to normal or near normal levels in children and adults for 3 and 4 days after injection, respectively. However, real-world evidence regarding clinical outcomes of switching from efmoroctocog alfa to efanesoctocog alfa, particularly in paediatrics, is limited. This report evaluated treatment patterns and outcomes of switching from efmoroctocog alfa to efanesoctocog alfa prophylaxis in children with haemophilia A in the United Arab Emirates (UAE).

Methods: This retrospective, single-centre report evaluated , male haemophilia A patients (median age =9.0 years [IQR: 7.3–15.5]) transitioning from efmoroctocog alfa to efanesoctocog alfa prophylaxis at Tawam Hospital, UAE. All patients received efmoroctocog alfa prophylaxis during the pre-switch period (January 2023 to July 2024) before transitioning to efanesoctocog alfa in August 2024 and were followed up until March 2025 (observation period). All patients were inhibitor-negative at baseline. Primary efficacy was assessed through annualised bleeding rates (ABR). Secondary outcomes included joint bleeding frequency, inhibitor occurrence, and dosing patterns. Adherence to efanesoctocog alfa was monitored through infusion logs and pharmacy refill records. Patients were considered fully adherent if they received all scheduled doses throughout the observation period.

Results: Twenty-onepatients (95.5%) had severe disease. , half of the cohort experienced joint bleeding episodes; eight patients (36.4%) experienced one joint bleed, and three patients (13.6%) experienced two or more bleeds. The knee was the most frequently affected joint (54.6%), followed by the elbow (18.2%). The median prophylactic dose of efanesoctocog alfa was 57.1 IU/kg (IQR: 50.0–63.9). Patients received efanesoctocog alfa for eight months. , 100% of patients achieved a zero ABR, with no reported treatment-emergent adverse events or discontinuations. All patients demonstrated 100% adherence to the prescribed once weekly efanesoctocog alfa regimen. No active inhibitors or treatment-emergent adverse events were observed.

Conclusions: Switching from efmoroctocog alfa to once weekly efanesoctocog alfa prophylaxis demonstrated highly effective bleeding prevention and a favourable safety profile in paediatric patients. These findings highlight efanesoctocog alfa's potential and long-term clinical outcomes in routine paediatric haemophilia A management, warranting further exploration through larger, prospective studies.

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2025
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