Von Willebrand Disease, Type 3

This is a Phase III, multicenter, open-label clinical study designed to evaluate the efficacy, safety, pharmacokinetics, and pharmacodynamics of emicizumab prophylaxis in participants aged 1 month and above, who have been diagnosed with Type 3 von Willebrand disease (VWD). Participants on prior standard of care (SOC) on-demand therapy will be assessed via a randomized comparison (Arm A - emicizumab prophylaxis and Arm B - continuation of SOC on-demand therapy), while participants on prior SOC prophylactic therapy (Arm C - emicizumab prophylaxis) will be assessed via intra-participant analysis with data obtained from the preceding non-interventional study (NIS), WP45335 (NCT06883240).

Von Willebrand Disease (VWD) is the most common inherited bleeding disorder affecting up to 0.1% of the population, is usually characterized by mucocutaneous bleeding, HMB, surgical bleeding or other hemostatic challenges. Severe bleeding events require VWF concentrates administered solely through intravenous access. Emicizumab (Hemlibra) is a monoclonal bispecific antibody developed to bind activated FIX and FX and mimic FVIII cofactor functionality. Hemlibra is administered via subcutaneous injection rather than intravenous infusion. The hypothesis of this study is that Emicizumab is safe and efficacious for prophylaxis in severe VWD and concomitant VWD/hemophilia patients.