New Treatment for Acquired Thrombotic Thrombocytopenic Purpura: Caplacizumab

Immune-mediated deficiency of the von Willebrand factor–cleaving protease ADAMTS13 allows unrestrained adhesion of von Willebrand factor multimers to platelets and microthrombosis. This results in thrombocytopenia, hemolytic anemia, and tissue ischemia. These are the hallmarks of  acquired thrombotic thrombocytopenic purpura (TTP).

Caplacizumab is an anti–von Willebrand factor humanized. Caplacizumab is not a full antibody, but just a fragment if it, as you can see in the video below. It inhibits interaction between von Willebrand factor multimers and platelets.

In this double-blind, controlled trial, 145 patients with TTP received caplacizumab (10-mg intravenous loading bolus, followed by 10 mg daily subcutaneously) or placebo during plasma exchange and for 30 days thereafter.

The median time to normalization of the platelet count was shorter with caplacizumab than with placebo (2.69 days vs. 2.88 days). Patients who received caplacizumab were 1.55 times as likely to have a normalization of the platelet count as those who received placebo.

Treatment with caplacizumab in TTP was associated with:

- faster normalization of the platelet count
- lower incidence of a composite of TTP-related death, recurrence of TTP, or a thromboembolic event
- lower rate of recurrence of TTP



References:

Caplacizumab Treatment for Acquired Thrombotic Thrombocytopenic Purpura | NEJM https://buff.ly/2MMYBLr