Ablynx announced that the Food and Drug Administration (FDA) has granted Fast Track designation for caplacizumab for the treatment of acquired thrombotic thrombocytopenic purpura (aTTP).
The Phase 2 TITAN study (n=75) evaluated the safety and efficacy of caplacizumab with standard of care of plasma exchange and immunosuppression. The study met its primary endpoint (P=0.005) with caplacizumab demonstrating a 39% reduction in time to platelet count normalization vs. placebo. Also, treatment with caplacizumab decreased recurrences of aTTP by 71% vs. placebo.
A post-hoc analysis of study data further showed that a clinically meaningful lower proportion of caplacizumab-treated patients had one or more major thromboembolic events or died vs. placebo (11.4% vs. 43.2%). In addition, fewer patients in the caplacizumab group vs. placebo were refractory to treatment (5.7% vs. 21.6%).
Caplacizumab is a first-in-class bivalent, anti-von Willebrand factor (vWF) Nanobody in development to treat aTTP, a life-threatening, autoimmune blood clotting disorder. It works by blocking the interaction of ultra-large vWF multimers with platelets, thus affecting platelet aggregation and the accumulation of micro-clots that cause severe thrombocytopenia, tissue ischemia, and organ dysfunction in aTTP.
There is currently no treatment for aTTP and conventional treatment includes plasma exchange and immunosuppressants. The current Phase 3, randomized, double-blind, placebo-controlled HERCULES study will evaluate the safety and efficacy of caplacizumab in patients with aTTP when given in addition to standard-of-care. The primary endpoint of the study is time to platelet count normalization; secondary endpoints include a composite endpoint consisting of TTP-related mortality, recurrence of TTP and major thromboembolic events during study drug treatments, among others.
An additional 3-year follow-up study for patients in the HERCULES study is also in the works and will evaluate the long-term safety and effectiveness of caplacizumab.
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