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

Authors: Gouider E, Klukowska A, Maes P, Platokouki H, Snia Pujol S, Henriet C, Bridey F, Goudemand J

Affiliations: Haemophilia Centre, Aziza Othmana Hospital, University Tunis El Manar, Tunis , Tunisia ; Department of Oncology, Paediatric Haematology, Clinical Transplantology and Paediatrics of Warsaw Medical University, Warsaw, Poland; University Hospital of Antwerp, Paediatric Haematology and Oncology Department, Antwerp, Belgium; Haemophilia-Centre-Haemostasis Unit, Aghia Sophia Children’s Hospital, Athens, Greece; Clinical Development, Laboratoire Français du Fractionnement et des Biotechnologies (LFB), Les Ulis, France ; Formerly Clinical Development, Laboratoire Français du Fractionnement et des Biotechnologies (LFB), Les Ulis, France; Department of Haemostasis and Transf usion, Lille University Hospital, Lille, France

Publication: Blood Transfusion ; 2023 ; 21. 83–92

Abstract: BACKGROUND – Plasma-derived von Willebrand factor (VWF) (Wilfactin®, 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®, 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® 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®. 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® provides a safe and effective treatment in patients <6 years of age with severe VWD.