Immunogenicity of a Plasma-Derived Von Willebrand Factor/Factor VIII Concentrate during the Wil-31 Prophylaxis Study in Patients with Von Willebrand Disease

Background: Long-term prophylaxis with a von Willebrand factor (VWF) concentrate is recommended in people with von Willebrand disease (VWD) with a history of frequent and severe bleeds. The WIL-31 study demonstrated the efficacy of prophylaxis with a plasma-derived VWF/factor VIII (pdVWF/FVIII) concentrate containing VWF and FVIII in a 1:1 activity ratio (wilate ®) in adults and children with VWD of all types. The primary endpoint was met, showing a decrease in mean total annualized bleeding rate (ABR) of 84% compared with prior on-demand treatment.