Caplacizumab may enhance treatment of aTTP

The incidence of aTTP recurrence during the follow-up period alone was 9.1% (n=6) in the caplacizumab arm and 0% (n=0) in the placebo arm.

A third key secondary endpoint was the percentage of patients with refractory aTTP, which was 0% (n=0) in the caplacizumab arm and 4.2% (n=3) in the placebo arm (P=0.0572).

Safety

The number and nature of treatment-emergent adverse events (AEs) were similar between the treatment arms, according to Ablynx. The proportion of patients with at least 1 treatment-emergent AE was 97.2% in the caplacizumab arm and 97.3% in the placebo arm.

The proportion of patients with at least 1 study-drug-related AE was 57.7% in the caplacizumab arm and 43.8% in the placebo arm. The rate of discontinuation due to at least 1 AE was 7.0% and 12.3%, respectively.

The incidence of bleeding-related AEs was higher in the caplacizumab arm than the placebo arm—66.2% and 49.3%, respectively. However, most bleeding-related events were mild or moderate in severity.

The proportion of patients with at least 1 serious AE was 39.4% (n=28) in the caplacizumab arm and 53.4% (n=39) in the placebo arm. The proportion of patients with at least 1 study-drug-related serious AE was 14.1% (n=10) and 5.5% (n=4), respectively.

During the treatment period, there were no deaths in the caplacizumab arm and 3 deaths in the placebo arm. There was 1 death in the caplacizumab arm during the follow-up period, but it was considered unrelated to caplacizumab.