Zero incidence of factor VIII inhibitors and successful haemostatic response in previously factor VIII-treated patients with haemophilia A switching to turoctocog alfa in a noninterventional study

Introduction: Turoctocog alfa (NovoEight^®) is a B-domain-truncated recombinant factor VIII (FVIII) approved for patients with haemophilia A. Aim: To investigate the long-term safety and efficacy of turoctocog alfa in routine clinical practice. Methods: Guardian 5 was a prospective, multinational, non-interventional, post-authorisation safety study. Male previously treated patients (> 150 exposure days [EDs]) of any age with severe/moderately severe haemophilia A (FVIII ≤ 2%) and a negative inhibitor test prior to first dosing (independent of FVIII-inhibitor history) were included to receive prophylaxis or on-demand treatment. The primary endpoint was the proportion of patients developing FVIII inhibitors (≥.6 Bethesda Units [BU]) after baseline visit, measured as per routine practice of each study site during clinic visits. Secondary endpoints included haemostatic effect, annualised bleeding rate (ABR), and adverse reactions assessment. The study concluded when 50 patients reached 100 EDs/patient minimum. Results: Seventy patients were screened and 68 exposed to turoctocog alfa; 63 (92.6%) were on prophylaxis and five received on-demand treatment. Six (8.8%) patients reported a history of positive inhibitors. During the study, patients were exposed to turoctocog alfa for a mean (standard deviation) of 131.9 (99.0) days/patient. Fifty-five of 58 patients who completed the study were tested for FVIII inhibitors; no positive tests were reported. Overall success rate of turoctocog alfa for treatment of bleeds was 87.3%. Among patients receiving prophylaxis, median (range) ABR was 1.97 (.0–25.5) bleeds/year; estimated ABR (negative binomial model) was 3.65 (95% confidence interval: 2.53–5.25). Conclusion: Turoctocog alfa was safe and efficacious for haemophilia A treatment in routine clinical practice.