The late-stage trial evaluated it against placebo in 145 aTTP patients who were also given standard-of-care treatment.
Caplacizumab, at any given time during the trial, demonstrated statistically significant reduction in time to platelet count response, which was the defined primary endpoint.
Patients subjected to caplacizumab were shown to be 50% more probable to achieve platelet count response.
Ablynx chief medical officer Dr Robert K. Zeldin said: “Patients with aTTP are at risk for significant morbidity and early death. We believe these positive Phase III study results confirm the potential for caplacizumab to address the high unmet medical need in the treatment of aTTP and to have a meaningful impact on the lives of affected patients.
“We continue to analyse the data and look forward to sharing the results with regulatory authorities and the scientific community.”
During the trial, Ablynx’s blood disease drug also registered 74% relative reduction in the percentage of patients with aTTP-related death, a recurrence of the disease, or at least one significant thromboembolic event.
Caplacizumab recorded 67% relative reduction in the percentage of patients with recurrence of aTTP during the overall trial period.
The drug’s safety profile was found to be in line with the results of its phase 2 trial TITAN and its mechanism of action.
Ablynx says that it will use the HERCULES data to push for the approval in Europe and the US.
Ablynx CEO Dr Edwin Moses said: “These results strengthen our resolve to obtain marketing approval as quickly as possible so that caplacizumab rapidly becomes available to patients suffering from this severe disease for which there is currently no approved drug available."
Caplacizumab, which is intended to be given intravenously, prevents the interaction of ultra-large vWF multimers (ULvWF) with platelets. Thereby, the drug immediately impacts platelet aggregation and the subsequent formation and accumulation of the micro-clots that are behind severe thrombocytopenia, tissue ischemia and organ dysfunction in aTTP.
Image: Caplacizumab – Ablynx's anti-vWF Nanobody. Photo: courtesy of Ablynx.