PB3417 Evidence of efficacy for prophylaxis with plasma-derived VWF/FVIII 1:1 in children with severe von Willebrand Disease: WIL-33 extends WIL-31 paediatric findings to <6 years

Routine prophylaxis with von Willebrand factor (VWF) is recommended for individuals with severe, symptomatic von Willebrand disease (VWD); however, prospective evidence in children aged <6 years is scarce. WIL-31, the largest prospective prophylaxis study in VWD to date, demonstrated substantial bleeding reduction and a favourable safety profile with a plasma-derived (pd) VWF/FVIII 1:1 concentrate in patients aged ≥6 years, including paediatric subgroups. WIL-33 extends this evidence to children <6 years with severe VWD, supporting an integrated assessment of prophylaxis outcomes across the paediatric age spectrum.