Efficacy and safety of plasma-derived von Willebrand factor/factor VIII concentrate (wilate) prophylaxis in children and adolescents with von Willebrand disease - WIL-31 study post hoc analysis.

BACKGROUND

Prophylaxis with von Willebrand factor is recommended in people with severe von Willebrand disease (VWD), regardless of age. WIL-31, the only prospective study with an on-demand run-in study as an intraindividual comparator, demonstrated the efficacy and safety of prophylaxis with the plasma-derived von Willebrand factor/factor VIII concentrate wilate (Octapharma) in adults and children with VWD of all types. Prophylaxis is often considered in young children and adolescents with severe VWD and recurrent bleeding, although limited data support this strategy.

OBJECTIVES

To assess the efficacy of wilate prophylaxis in children (6-11 years) and adolescents (12-16 years) in WIL-31.

METHODS

Patients received 20 to 40 IU/kg (Octapharma) wilate prophylaxis 2 to 3 times weekly for 12 months. Results were compared with prospective on-demand treatment.

RESULTS

Mean total annualized bleeding rates (ABRs) during on-demand vs prophylaxis were 32.5 vs 3.7 in children (n = 9) and 28.9 vs 4.3 in adolescents (n = 6), representing reductions of 89% and 85%, respectively. All 34 bleeds in children, and 20/26 (77%) bleeds in adolescents were minor. Mean spontaneous ABRs during prophylaxis were 2.5 in children and 1.5 in adolescents. The most common bleeding site in both groups and across all VWD types was the nose. ABRs were reduced further during the second 6 months of prophylaxis vs the first 6 months. During the second 6 months, 78% of children and 67% of adolescents had zero spontaneous bleeds. No serious adverse events related to study treatment or thrombotic events were observed.

CONCLUSION

wilate prophylaxis was efficacious and well-tolerated in children and adolescents with all types of VWD.