Positive results of the Phase III HERCULES trial of Sanofi’s Cablivi (caplacizumab) in adults with acquired thrombotic thrombocytopenic purpura (aTTP) have been published in the New England Journal of Medicine (NEJM).

In the trial, treatment with Cablivi was associated with a 74% reduction in aTTP-related death, recurrence of aTTP, or at least one major thromboembolic event, compared with placebo.

The study, in which 145 patients were randomly assigned to Cablivi or placebo in conjunction with plasma exchange and immunosuppression, also found that Cablivi significantly reduced the time to platelet count normalisation, and at any given time point during the study, patients receiving the drug were 1.55 times more likely to achieve normal platelet counts than patients on placebo.

Cablivi is an anti-vWF Nanobody, which works by inhibiting the interaction between ultra-large von Willebrand Factor (vWF) multimers and platelets and, therefore, stops the formation and accumulation of the micro-clots that cause the thrombocytopenia, tissue ischemia, and organ dysfunction in aTTP.

Marie Scully, professor of haematology at University College London Hospitals, and lead author of the HERCULES study, commented: "aTTP is a life-threatening disease, and the current treatment options do not fully halt the extensive clot formation in small blood vessels throughout the body, leaving patients at risk for significant morbidity and early death.

"These results demonstrate that Cablivi has the potential to address a major unmet medical need and to help those facing the potentially devastating consequences of this disorder."

aTTP is characterised by extensive clot formation in small blood vessels throughout the body, leading to severe thrombocytopenia (very low platelet count), microangiopathic haemolytic anemia (loss of red blood cells through destruction), ischemia (restricted blood supply to parts of the body) and widespread organ damage, especially in the brain and heart.