Caplacizumab to treat immune-mediated thrombotic thrombocytopenic purpura

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare and life-threatening disease characterized by microangiopathic hemolytic anemia, thrombocytopenia and multiorgan failure, resulting from autoantibody-mediated severe A disintegrin and metalloproteinase with thrombospondin motifs 13 (ADAMTS13) deficiency. In spite of treatment with plasma exchange and immunosuppression, patients remain at risk of exacerbations, refractoriness and death. Caplacizumab (Cablivi; Ablynx, a Sanofi company), a nanobody targeting von Willebrand factor (vWF), has been recently approved in the E.U. and the U.S. as the first therapeutic specifically indicated for the treatment of adults experiencing an episode of iTTP. Caplacizumab blocks the interaction of all multimers with platelets and, therefore, has an immediate effect on platelet aggregation and the ensuing formation and accumulation of platelet-rich microthrombi. This immediate effect of caplacizumab has the potential to protect the patient from tissue ischemia and organ dysfunction while the underlying disease process resolves. We detail here the preclinical and clinical data on caplacizumab for iTTP, including the recent studies that led to approval by the U.S. Food and Drug Administration (FDA) in 2019.