FDA grants fast-track status for Ablynx’s caplacizumab to treat aTTP

Belgian biopharmaceutical company Ablynx has received fast-track designation from the US Food and Drug Administration (FDA) for its caplacizumab treatment for acquired thrombotic thrombocytopenic purpura (aTTP).

Caplacizumab is Ablynx’s first-in-class anti-von Willebrand factor (vWF) Nanobody that is currently being developed to treat patients with aTTP, a life-threatening, autoimmune blood clotting disorder.

aTTP results in extensive clot formation in small blood vessels throughout the body, leading to thrombocytopenia, ischemia and widespread organ damage, particularly in the brain and heart.

Ablynx chief medical officer Dr Robert Zeldin said: "The designation of fast-track status by the FDA is recognition of the high unmet medical need in patients with aTTP and the potential for caplacizumab to improve outcomes in this very severe disease.

"We look forward to continuing to work with the FDA and accelerating the development of caplacizumab as potentially the first therapeutic specifically indicated for the treatment of aTTP."

Caplacizumab is a bivalent anti-vWF Nanobody that blocks the interaction of ultra-large vWF multimers (ULvWF) with platelets.

This creates an immediate effect on platelet aggregation, and the ensuing formation and accumulation of the micro-clots that cause the severe thrombocytopenia, tissue ischemia and organ dysfunction in an aTTP patient.

The treatment has the capability to protect the patient from the manifestations of the disease while the underlying disease process resolves.

The capability of the treatment has been evaluated in the Phase II TITAN study, which involved 75 patients with aTTP.

The trial demonstrated that caplacizumab was well-tolerated and the primary endpoint was met, resulting in a 39% reduction in time to platelet count normalisation when compared to placebo.

The treatment is currently being further evaluated in the randomised, double-blind, placebo-controlled Phase III HERCULES trial that will study the efficacy and safety of caplacizumab in patients with aTTP when administered in addition to the standard-of-care.