PB0235 - Phase 3 Study of the Efficacy, Pharmacokinetics, Immunogenicity and Safety of von Willebrand Factor/Factor VIII Concentrate in Patients with Severe von Willebrand Disease under 6 Years of Age

Sunday, June 25, 2023

18:30 – 19:30 ET

Room: Exhibition

Presenting Author(s)

Akshat Jain

Director Inherited Bleeding Disorders and Hemoglobinopathies Program
Loma Linda University School of Medicine Center of Excellence for Bleeding Disorders
California, California, United States

Co-Author(s)

TW

Tarja-Elina Weisz

Clinical Trial Manager Clinical Research & Development Haematology
Octapharma Pharmazeutika Produktionsges.m.b.H
Vienna, Wien, Austria
Cristina Solomon, MD MBA

Vice President Clinical R&D Haematology
Octapharma AG
Lachen, Schwyz, Switzerland
VV

Vladimir Vdovin

Chief Specialist on Hemophilia-Haematology
Morozovskaya Children's City Clinical Hospital
Moscow, Moskva, Russia
PZ

Pavel Zharkov

Pediatrician
Dmitry Rogachev National Research Center of Pediatric Hematology
Moscow, Moskva, Russia
ZT

Zorica Trajkova-Antevska

Head of department
PHI University Clinic for child diseases
Skopje, Skopje, Macedonia
EZ

Ester Zapotocka

Director of hemophilia
University Hospital Motol
Prague, Hlavni mesto Praha, Czech Republic

Background: Von Willebrand disease (VWD) is a common inherited hemorrhagic disorder affecting around 1 in 100 individuals. Prophylactic von Willebrand factor (VWF) replacement therapy in patients with severe VWD, including children, has demonstrated efficacy.

Aims: The WIL-33 study investigates the efficacy, pharmacokinetics (PK) and safety of a plasma-derived, stable, highly purified, double virus inactivated VWF/factor VIII (FVIII) concentrate (Octapharma) in pediatric patients aged < 6 years with severe VWD.

Methods: WIL-33 is an open-label, prospective, non-controlled, international, multi-center Phase 3 study of VWF/FVIII concentrate efficacy as prophylactic treatment of patients aged < 6 years with severe VWD (defined as screening VWF ristocetin cofactor activity < 20%). WIL-33 plans to enroll 12 patients regardless of prior treatment, of which eight should be evaluable for the primary endpoint; at least four should have hereditary type 3 VWD. Remaining patients can be diagnosed with severe type 2 (except 2N) or severe type 1 VWD. All sites must have local ethics committee approval and written informed consent from parents. The primary endpoint is total annualized bleeding rate (ABR) over the 12-month prophylactic treatment period. Secondary efficacy, safety and exploratory endpoints are described in Table 1. Dosing for PK, prophylactic treatment, treatment of bleeding episodes (BEs) and for surgeries, as well as study assessments, are shown in Figure 1. Patients will record BEs in a diary, which will be used to calculate ABR.

Results: To date, 6 patients have been recruited at 6 sites in 5 countries. Clinical end is expected by mid-2024, with results anticipated by end-2024.

Conclusion(s): Prophylactic treatment is standard of care in other inherited bleeding disorders to prevent bleeding in patients; however, this is not well characterized in patients with VWD, especially in young children. WIL-33 will provide data on the efficacy of prophylactic treatment in pediatric patients aged < 6 years with severe VWD.