Efficacy and safety of von Willebrand factor concentrate almost devoid of factor VIII (Wilfactin®) in paediatric patients under 6 years of age with severe von Willebrand disease

Background - Plasma-derived von Willebrand factor (VWF) (Wilfactin((R)), LFB, France) was developed for prophylaxis and treatment of haemorrhages in both adults and adolescents with von Willebrand disease (VWD). Replacement therapy in paediatric patients is a key element of the clinical trial programme. Material and methods - Patients aged <6 years with severe VWD were enrolled in a multinational, open-label study to evaluate the in vivo recovery for Wilfactin((R)), and its efficacy in preventing and treating bleeding episodes and during surgery. Overall haemostatic efficacy based on a 4-point scale was assessed by investigators. The treatment period >= 18 months investigated the long-term safety. Results - Nine patients, including 7 with type 3 VWD were exposed to treatment with Wilfactin((R)) for up to 4.2 years. Recovery of VWF in 7 patients (n=5 type 3, n=1 type 2, n=1 type 1) was 1.8 +/- 0.4 IU/dL per IU/kg. Of the 62 bleeds, 89% were controlled with one (73%) or two (16%) infusions of Wilfactin((R)). The median dose per infusion was 54 IU/kg. A factor VIII dose was co-administered in 1.6% of bleeds. "Excellent"/"Good" haemostatic efficacy was achieved in 90.3% of episodes. Six patients underwent 11 minor surgical interventions. Treatment duration was 1 day (range: 1-6 days) with a dose administered 30-60 minutes before procedure of 56 IU/kg (range: 41-106 IU/kg). Haemostasis was rated as "Excellent" in all surgeries. During 4-year prophylactic treatment in one patient, breakthrough bleeds were reported in 2.2% of infusions. No VWF inhibitors, thromboembolic events or allergic/anaphylactic-type reactions were observed following a total exposure of 770 days. Discussion - The results show that Wilfactin((R)) provides a safe and effective treatment in patients <6 years of age with severe VWD.