Summary

The safety and efficacy of sucrose-formulated recombinant factor VIII (rFVIII-FS; Kogenate® FS) under usual clinical practice were evaluated for 12 months in an observational, postmarketing surveillance study conducted at 214 treatment centres throughout Japan. The study included 631 patients with haemophilia A, 80% of whom had severe or moderately-severe disease (≤2% FVIII:C).Most patients (n=477;75.6%) had >100 prior exposure days (EDs), but the study also included 62 (9.8%) patients with <20 EDs who were at high risk for inhibitor development. A total of 71,240 infusions were administered during the observation (mean, 113 ± 108 per patient). Physicians rated efficacy and tolerability of rFVIII-FS as “very good” or “good” in >99% of patients. FVIII inhibitors were observed in seven patients (5 de novo; 1 persistent/fluctuating; 1 recurrent).The overall de novo inhibitor incidence was 0.8% (5/631; or 5/599 among the subgroup of patients with negative baseline titre and no known inhibitor history). De novo cases represented 3.2% (2/62) of patients with <20 EDs at enrollment (2/57 in the no inhibitor subgroup) and 0.2 % (1/477) of patients pretreated with >100 EDs (1/452 in the no inhibitor subgroup) at enrollment.The results of this large observational study demonstrate that rFVIIIFS is both safe and efficacious as used in the usual clinical setting for the treatment of Japanese patients with mild to severe haemophilia A.This study supports the efficacy of rFVIII-FS with an incidence of inhibitor formation no greater than in a comparable European study or previous phase III clinical studies.