Phase 4 Safety and Efficacy Study of Antihemophilic Factor (Recombinant) in Previously Treated Chinese Patients With Severe/Moderately Severe Hemophilia A

Abstract

Antihemophilic factor (recombinant) (rAHF; ADVATE®; Baxalta US Inc., a Takeda company, Lexington, MA, USA) is indicated for the treatment and prevention of bleeding in patients with hemophilia A. We aimed to assess the safety and efficacy of standard prophylaxis versus on-demand treatment with rAHF in previously treated Chinese patients with severe/moderately severe hemophilia A. This open-label, sequential, interventional, postapproval study (NCT02170402) conducted in China included patients of any age with hemophilia A with factor VIII (FVIII) level ≤2%. Patients received 6 months’ on-demand rAHF then 6 months’ rAHF prophylaxis (20-40 IU/kg every 48 ± 6 hours). The primary objective was percentage reduction in annualized bleeding rate (ABR) in the per-protocol analysis set (PPAS); secondary objectives included ABR by bleeding subtype, hemostatic efficacy, immunogenicity, and safety. Of 72 patients who received ≥1 rAHF dose, 61 were included in the PPAS. Total ABR was lower during prophylaxis (mean 2.5, 95% CI 1.5-3.7; median 0) versus on-demand treatment (mean 58.3, 95% CI 52.5-64.7; median 53.9), representing a 95.9% risk reduction. Similar findings in favor of prophylaxis were observed for all types of bleeding event by cause and location. rAHF hemostatic efficacy was rated as “excellent”/“good” in 96.1% of treated bleeding events. Transient FVIII inhibitors (0.6-1.7 BU) in 4 patients resolved before study end; no unexpected safety issues were observed. rAHF prophylaxis in this study of previously treated Chinese patients with severe/moderately severe hemophilia A resulted in a clear reduction in bleeding events versus rAHF on-demand treatment, with no change in safety profile.