Emicizumab prophylaxis in patients with haemophilia A with and without inhibitors.

Introduction: Emicizumab is a bispecific monoclonal antibody that mimics factor VIII (FVIII) by binding to factors IXa and X to promote hemostasis in haemophilia A (HA) and HA with inhibitors (HA-I). As emicizumab differs biochemically from FVIII, there is interest in its real-world haemostatic efficacy.

Aim: To describe real-world patient experience with emicizumab by retrospective chart review.

Methods: We reviewed medical records of patients cared for at the Hemophilia Center of Western PA, who initiated emicizumab following its licensure, and on whom bleeding events and factor use were available. Comparisons between groups were done by Student's t test for continuous data and by chi-square or Fisher's exact test for discrete data.

Results: A total of 42 patients whose charts were reviewed included 18 (42.9%) with HA and 24 (52.1%) with HA-I. Groups were similar in age, 17 (40.5%) <18 years, race, and haemophilia severity, and initiated weekly subcutaneous emicizumab 1.5 mg/kg, following 4-week induction. Fourteen (33.3%) experienced at least one breakthrough bleed, of which 11 (44.0%) were joint bleeds, with an annualized bleed rate (ABR), 0.9 ± 0.3, not different between groups, P = .251. Surgical procedures were performed in 10 (23.8%), of whom 4 (40.0%) had postoperative bleeding and one developed postoperative thrombosis in association with FEIBA despite emicizumab discontinuation 1 month preoperatively. Local skin reactions occurred in three and headache in one. Overall, 85.0% of those who rated their health indicated it was improved.

Discussion: Despite breakthrough bleeds and postoperative thrombosis associated with emicizumab, most HA and HA-I experienced improved health.