Changes in thromboelastography measurement results of emicizumab-treated patients with hemophilia A

Abstract

HEMLIBRA^® (emicizumab), which is used as a novel treatment for hemophilia A, is a recombinant humanized bispecific monoclonal antibody for factor IX (FIXa) and factor X (FX). By mimicking the factor VIII (FVIIIa) cofactor activity, it significantly decreases bleeding events. Emicizumab affects the results of activated partial prothrombin time (APTT), which is commonly used in coagulation assays, and the APTT-based assays of FVIII activity. We evaluated changes in the assay results of hemophilia A patients without inhibitors who have been tested by thromboelastography (TEG^®6s). Blood samples were collected from hemophilia A patients without inhibitors who started emicizumab administration at our hospital. We compared the results of TEG^®6s and coagulation assays before and after emicizumab administration. The tracing waveform of TEG^®6s after emicizumab administration showed improvement in all patients, and the result several months after the administration also showed that the improved state was maintained. Although it is necessary to confirm these results in a larger number of cases and the results when a bleeding event occurs, it is suggested that the TEG^®6s result may be used as a tool for understanding the blood coagulation dynamics of emicizumab-treated hemophilia A patients.