OC 71.4 - Three-Year Efficacy Assessment of Emicizumab in Hemophilia A Patients without Inhibitors: A Tailored Dose Titration Approach

Background: Emicizumab, a factor VIII (FVIII) mimetic, has been approved for hemophilia A patients, both with and without inhibitors. Administered subcutaneously, it achieves stable plasma levels following a loading dose (3 mg/kg/week) in the initial four weeks. However, dosing according to the label may lead to drug wastage or overdose due to discrepancies between calculated weighed doses and vial contents. Recent studies advocate for monitoring to optimize doses and vials, with potential economic benefits. Limited evidence exists on the long-term joint health of patients under a cost-effective emicizumab regimen.

Aims: Assess emicizumab's three-year efficacy in hemophilia A without inhibitors, optimizing dosing for cost-effectiveness, monitoring bleeding rates, and preserving joint health for personalized, safe management.

Methods: A retrospective analysis of 15 patients (9 children, 6 adults) with severe hemophilia A without inhibitors was conducted. Patients were on prophylaxis with factor VIII concentrates. Vials were optimized to reduce waste and facilitate home administration. Emicizumab levels were measured at 12, 24, and 36 months. The study assessed bleeding rates, joint health, and conducted a pharmacoeconomic analysis comparing standard dosing to optimized doses.

Results: After three years, median emicizumab levels were 55.8 μg/ml, with monthly doses of 5.04 mg/kg in children and 5.8 mg/kg in adults. The annualized bleeding rate was 1.3, with no joint bleeding observed. Spontaneous bleeds occurred in 6 patients, of which 38% were treated. Traumatic bleeds (20 incidents in 10 patients) were all treated. Joint evaluation in children revealed no new synovitis or arthropathy. The pharmacoeconomic study indicated a significant reduction in dosage, resulting in a cost saving of 241,200 euros annually.

Conclusion(s): Monitoring allowed for the maintenance of therapeutic plasma levels, vial optimization, cost reduction, and preservation of joint health. This study highlights the importance of a personalized and cost-effective approach in the long-term management of hemophilia A patients without inhibitors treated with emicizumab.