Immune tolerance induction with a factor VIII concentrate containing von Willebrand factor (Haemoctin SDH®) in 14 patients with severe haemophilia A

von Willebrand factor modulates immune complexes and the recall response against factor VIII in a murine hemophilia A model

Achieving tolerance toward factor VIII (FVIII) remains an important goal of hemophilia treatment. Up to 40% of patients with severe hemophilia A (HA) develop neutralizing antibodies against FVIII, and the only proven treatment to achieve tolerance is infusion of FVIII over prolonged periods in the context of immune tolerance induction. Here, we addressed the role of von Willebrand factor (VWF) as a modulator of anti-FVIII antibody effector functions and the FVIII-specific recall response in an HA mouse model. Analytical ultracentrifugation was used to demonstrate formation of FVIII-containing immune complexes (FVIII-ICs). VWF did not fully prevent FVIII-IC formation but was rather incorporated into larger macromolecular complexes. VWF prevented binding of FVIII-ICs to complement C1q, most efficiently when it was preincubated with FVIII before the addition of antibodies. It also prevented binding to immobilized Fc-γ receptor and to bone marrow-derived dendritic cells. An in vitro model of the anti-FVIII recall response demonstrated that addition of VWF to FVIII abolished the proliferation of FVIII-specific antibody-secreting cells. After adoptive transfer of sensitized splenocytes into immunocompetent HA mice, the FVIII recall response was diminished by VWF. In summary, these data indicate that VWF modulates the formation and effector functions of FVIII-ICs and attenuates the secondary immune response to FVIII in HA mice.

octanate®: over 20 years of clinical experience in overcoming challenges in haemophilia A treatment

Treatment of haemophilia A with FVIII replacement has evolved over the past decades to adapt to the needs of patients. octanate®, a plasma-derived, double virus-inactivated, von Willebrand factor (VWF)-containing FVIII concentrate, has been used in clinics worldwide for over 20 years. First licensed in 1998 in Germany, octanate® is approved in over 80 countries for the prevention and treatment of bleeding and for surgical prophylaxis in patients with haemophilia A, and in over 40 countries for immune tolerance induction (ITI). The manufacturing process for octanate® was developed to ensure high viral safety and effectively eliminates both enveloped and nonenveloped viruses. Over the past 20 years, the excellent safety and efficacy of octanate® have been demonstrated in pivotal clinical trials in adult and paediatric previously treated patients (PTPs) for on-demand treatment, prophylaxis and as surgical cover. Importantly, octanate® has displayed low immunogenicity in previously untreated patients (PUPs), with only 9.8% of PUPs developing FVIII inhibitors. octanate® has also shown to be highly effective in inhibitor elimination when used as ITI therapy. In a population of patients with high risk of ITI failure, success was achieved in 79.2% of patients (70.8% complete success), even when using exceptionally stringent success criteria. No relapses were observed. Here we present an overview of the clinical data with octanate® that support its use in a range of patient populations and clinical indications.

Human von Willebrand factor/factor VIII concentrates in the management of pediatric patients with von Willebrand disease/hemophilia A

Several plasma-derived intermediate and high-purity concentrates containing von Willebrand factor (VWF) and factor VIII (FVIII) are currently available. The main role of these products in the management of the pediatric population is represented by the replacement therapy in patients with severe or intermediate forms of von Willebrand disease, in whom other treatments are ineffective or contraindicated. Another important role of VWF/FVIII concentrates in children may be their use in immune tolerance induction (ITI) protocols. ITI is particularly recommended for hemophilia A children who have developed an inhibitor against FVIII, currently the most serious complication of substitutive treatment in hemophilia. Although recombinant concentrates may represent the preferred option in children with hemophilia A, VWF/FVIII concentrates may offer an advantage in rescuing patients who failed previous ITI.