Critical Review of the Pivotal Studies of Four rFVIII Products for the Treatment of Hemophilia A Patients: The Role of Octocog Alfa

INTRODUCTION: Hemophilia A is a rare congenital bleeding disorder caused by a deficiency of clotting factor VIII (FVIII). The severe form of the disease is characterized by spontaneous bleeds, especially into the joints. Prophylaxis, based on regularly intravenous administration of the missing factor to avoid hemorrhages, represents the gold standard of treatment. In recent years, new products that significantly improve the treatment management options for patients with hemophilia have become available in the market. OBJECTIVE: To critically evaluate the pivotal studies of recombinant FVIII (rFVIII) products, approved in Europe within the first half of 2018 having obtained the indication for a prophylaxis dosing regimen based also on a twice weekly infusion frequency or even less, highlighting their limitations or strengths. METHODS: A systematic literature search was conducted, and several databases (PubMed and Embase) were consulted. RESULTS: Nine clinical trials involving patients with severe hemophilia A without inhibitor were included in this analysis. Four rFVIII products (Elocta (R), Biogen, Cambridge, MA, USA; Kovaltry (R), Bayer HealthCare Pharmaceuticals, Germany; Afstyla (R), CSL Behring GmbH, Germany; Adynovi (R), Baxalta Innovation GmbH, Austria) with different pharmacokinetic profiles were evaluated. The trials included in this analysis had different designs and heterogeneous methods were utilized to assess the study outcomes. The baseline characteristics of the patients enrolled in the studies were also often different and sometimes not adequately described. LEOPOLD II, a trial to compare prophylaxis to on-demand therapy with an unmodified rFVIII product (Kovaltry (R), octocog alfa), was the only completely randomized trial that enrolled a more critical patient population in terms of compromised joint condition than the other studies. Based on these side-by-side comparison, Octocog alfa reported similar efficacy, in terms of annualized bleeding rate, to the other rFVIII products, including extended half-life. CONCLUSIONS: Even without structural modifications, octocog alfa may be considered a useful treatment option for two times a week prophylaxis in a selected population of haemophilia patients.