Efficacy and Safety of Prophylaxis With a Plasma‐Derived von Willebrand Factor/Factor VIII Concentrate (Wilate) in Patients With Type 3 von Willebrand Disease—A WIL‐31 Study Sub‐Analysis

OBJECTIVES: The WIL-31 study demonstrated efficacy and safety of prophylaxis with the plasma-derived von Willebrand factor/factor VIII concentrate wilate in von Willebrand disease (VWD) of all types and was the only prospective study with an on-demand run-in study as an intra-individual comparator. This subgroup analysis examines the efficacy of wilate prophylaxis in patients with type 3 VWD in WIL-31. METHODS: Patients received 20-40 IU/kg wilate prophylaxis 2-3 times weekly for 12 months. RESULTS: Twenty-two patients in WIL-31 had type 3 VWD. Mean total annualized bleeding rate (ABRs) during on-demand versus prophylaxis was 37.1 versus 5.2 (86% reduction). During prophylaxis, 115 bleeds occurred, most (95%) of which were minor; the most common bleeding site was the nose (40% of bleeds). Mean overall spontaneous ABRs during on-demand versus prophylaxis were 26.5 versus 2.8 (89% reduction); mean treated spontaneous ABRs were 20.3 versus 1.4, respectively (93% reduction). ABRs were reduced further during the second 6 months of prophylaxis versus the first 6 months. Results were consistent in subgroups by age. No serious adverse events related to study treatment and no thrombotic events were observed. CONCLUSIONS: Prophylaxis with wilate was effective and well tolerated in patients with type 3 VWD, in all age groups. TRIAL REGISTRATION: NCT04052698; https://clinicaltrials.gov/study/NCT04052698.