Clinical Study to Investigate the Efficacy and Safety of Wilate during Prophylaxis in Previously Treated Patients with Von Willebrand Disease (VWD)

Background: Inherited von Willebrand disease (VWD) is the most common inherited hemorrhagic disorder, with an estimated prevalence of 1 in every 100 individuals. Type 1 and type 3 (the most severe form) are characterized by a quantitative deficiency of von Willebrand factor (VWF) and type 2 arises from a qualitative deficiency of VWF. Treatment of VWD depends on the type and severity of the disease. Severe bleeding is reported in patients with all subtypes, leading to progressive joint disease as well as diminished quality of life (QoL). VWF/factor VIII (FVIII) concentrates have become the mainstay of VWD treatment for these patients with severe disease or for those patients in whom other treatments (e.g., desmopressin) are ineffective or contraindicated but this is broadly applicable only for on demand treatment.

Aims: The primary objective of this study is to determine the efficacy of VWF/FVIIII concentrate in the prophylactic treatment of previously treated patients with type 3, type 2 (except 2N), or severe type 1 VWD. Secondary objectives of this study will be to collect data to 1) Assess the VWF:Ac and VWF:Ag incremental IVR of VWF/FVIIII concentrate over time and, 2) Assess the safety and tolerability of VWF/FVIIII concentrate in this indication.

The study will also examine, the efficacy of VWF/FVIIII concentratein the treatment of breakthrough bleeding episodes (BEs), and in surgical prophylaxis, as well as the QoL during prophylaxis with VWF/FVIIII concentrate.

Methods: The study is planned to enroll 28 patients aged ≥6 years and with VWD type 1, 2A, 2B, 2M, or 3. Eligible patients must be receiving on-demand treatment with a VWF-containing product, with at least 1, and an average of ≥2, documented spontaneous BEs per month in the preceding 6 months requiring treatment with a VWF-containing product. This will be assessed as part of a run-in observational study to collect the bleeding profile prior to the start of prophylaxis.

From the beginning of the study, patients will receive prophylactic treatment with VWF/FVIIII concentrate for 12 months and record all BEs in a patient diary. Based on these data, the frequency of BEs and the annualized bleeding rate (ABR) under prophylactic treatment will be calculated.

Treatment efficacy of BEs will be assessed by the patient (together with the investigator in case of on-site treatment) using a 4-point scale (excellent, good, moderate, none)

In patients that undergo surgeries, efficacy of VWF/FVIIII concentratewill be assessed at the end of surgery by the surgeon and at the end of the postoperative period by the haematologist. In both cases, predefined assessment criteria will be used. In addition, an overall assessment of efficacy will be made at the end of the postoperative period by the investigator.

Results: Data will be monitored on an ongoing basis and the study is expected to end Q2 2021.

Conclusions: Prophylactic treatment in other congenital bleeding disorders is widely accepted as the standard of care to prevent bleeding and preserve QoL in patients but to date, this form of treatment in VWD is not well characterized. This study will provide data on the efficacy of prophylactic treatment in reducing the rate of bleeding and on the impact of prophylaxis on the QoL in VWD patients.