Author Interviews, Hematology, NEJM / 11.02.2016
Nanobody is Potentially First Targeted Therapy for TTP
MedicalResearch.com Interview with:
Dr. Filip Callewaert PhD
Senior Clinical Scientist
Clinical Development, Ablynx
Zwijnaarde, Belgium
Medical Research: What is the background for this study? What are the main findings?
Dr. Callewaert: Acquired thrombotic thrombocytopenic purpura (TTP) is a rare and life-threatening coagulation disorder, in which accumulation of ultra-large von Willebrand factor (ULvWF) multimers is implicated, leading to an increased risk of thrombus formation in small blood vessels due to excessive platelet aggregation. There are no approved pharmacological therapies for acquired TTP. Despite treatment with the current standard of care (plasma exchange and immunosuppressive therapy), mortality remains at 10-20% and there is significant neurological, cardiac, and renal morbidity.
Caplacizumab is a bivalent Nanobody that binds to the A1 domain of vWF thereby preventing vWF-mediated platelet aggregation. The clinical effects of caplacizumab were demonstrated in the phase II randomised, placebo-controlled TITAN study in 75 patients with acquired TTP. Compared to placebo, there was a nearly 40% reduction in median time to platelet count normalisation in the caplacizumab group (p = 0.005). Treatment with caplacizumab reduced the use of daily plasma exchange and prevented further consumption of platelets in microthrombi and small blood vessel occlusion. In addition, there were fewer recurrences of TTP requiring re-initiation of daily plasma exchange during treatment with caplacizumab (N=3) vs. placebo (N=11). The safety profile of caplacizumab was favorable, with a slightly higher tendency of mostly mild bleeding events.























