OC 63.4 - Bleeding Sites in von Willebrand Disease Patients on Prophylaxis with a Plasma-derived von Willebrand Factor/Factor VIII Concentrate – A Sub-Analysis of Data from the WIL-31 Study
Associate Professor of Pediatrics Emory University Decatur, Georgia, United States
Background: The WIL-31 study (NCT04052698) demonstrated the efficacy and safety of prophylaxis with a plasma-derived von Willebrand factor/factor VIII concentrate (pdVWF/FVIII; wilate®) in people with von Willebrand disease (VWD).
Aims: To analyse bleeding sites in WIL-31 by age and VWD type.
Methods: WIL-31 was a prospective, non-controlled, international phase 3 trial that enrolled 33 male/female patients aged ≥6 years with VWD type 1 (VWF:RCo < 30 IU/dL), 2 (except 2N) or 3. Prior to entering the study, patients had received on-demand treatment with any pdVWF/FVIII concentrate during a 6-month, prospective, observational, run-in study. Patients in WIL-31 received prophylaxis with 20–40 IU/kg pdVWF/FVIII 2–3 times per week for 12 months. The primary endpoint was >50% reduction in mean total annualised bleeding rate (ABR) during prophylaxis compared with on-demand treatment. In this post-hoc analysis patients were grouped by age (children 6–11 years old, adolescents 12–16 years old, adults ≥17 years old) or VWD type, and the number of breakthrough bleeds was calculated for the prophylaxis period.
Results: Of 33 patients, six (18%) had severe type 1, 5 (15%) had type 2, and 22 (67%) had type 3 VWD. Under prophylaxis there were 173 breakthrough bleeds (62% spontaneous) resulting in a mean spontaneous ABR of 3.2 (86.9% reduction versus on-demand treatment). Adults and VWD type 1 patients had the highest number of total (6.3 and 9.0, respectively) and spontaneous (4.2 and 7.3, respectively) bleeds per patient across the age and type groups. Regardless of age or VWD type, the nose was the most frequent bleed site in each group (Figure 1). No patient experienced a spontaneous arm, leg, or knee joint bleed.
Conclusion(s): Differences in bleed sites were observed based on age and VWD type. The nose was the most common bleed site regardless of age or VWD type.
