Caplacizumab for Acquired Thrombotic Thrombocytopenic Purpura

Patients with acquired thrombotic thrombocytopenic purpura (TTP) have von Willebrand factor (VWF)–mediated platelet aggregates that consume platelets and occlude vessels. Caplacizumab is an immunoglobulin fragment (nanobody) that blocks the interaction of VWF with platelets; a phase II trial showed that caplacizumab was safe and shortened the duration of TTP (NEJM JW Oncol Hematol Apr 2016 and N Engl J Med 2016; 374:511).

To confirm the role of caplacizumab in resolving the thrombocytopenia and other complications of TTP as well as its role in decreasing the risk for recurrence, investigators conducted an industry-sponsored, randomized, double-blind, placebo-controlled trial involving 145 patients with TTP.

The following results were reported…