Prophylaxis with recombinant von Willebrand factor in patients with type 3 von Willebrand disease: Results of a post hoc analysis from a phase 3 trial

Objectives: To describe efficacy/safety of recombinant von Willebrand factor (rVWF) prophylaxis in patients with type 3 von Willebrand disease (VWD). Methods: This post hoc analysis of a phase 3 open-label trial provides a more detailed analysis of adults with type 3 VWD, categorized based on prior treatment at screening: "Prior On-Demand (OD)" (OD VWF; ≥3 documented spontaneous bleeding events [BEs] requiring VWF in previous 12 months) or "Switch" (plasma-derived [pd] VWF prophylaxis for ≥12 months). Annualized bleeding rates (ABRs) were evaluated during 12 months of rVWF prophylaxis versus historical data from medical records. Results: In the Prior OD group (n = 10), mean spontaneous ABR (sABR) for treated BEs was reduced by 91.6% (ratio, 0.08; 95% CI, 0.02-0.45) versus mean historical sABR. In the Switch group (n = 8), mean sABR for treated BEs was reduced by 47% (ratio, 0.53; 95% CI, 0.08-3.62). One non-serious adverse event (AE) was considered possibly related to rVWF. No treatment-related, fatal, or life-threatening serious AEs were reported, and no patient developed VWF inhibitors. Conclusions: rVWF prophylaxis reduced sABR in type 3 VWD patients previously treated with OD VWF therapy, and maintained a similar level of hemostatic control in those switching from pdVWF prophylaxis to rVWF prophylaxis.