Global Coagulation Potentials and Breakthrough Bleeds in Emicizumab-Treated Hemophilia a Patients Were Similar to Mild Hemophilia a Patients

Emicizumab prophylaxis dramatically reduces bleeding events in severe patients with hemophilia A (PwHA) with and without FVIII inhibitors. Recently, some real-world experiences on PwHA with emicizumab prophylaxis have been reported. The effectiveness of emicizumab could be attributed to an earlier report that the coagulant potential in emicizumab at clinical dosage appeared to correspond to 10-15 IU/dL of factor VIII activity (FVIII:C) (Muto, JTH 2014), indicating that emicizumab enables to transform severe PwHA to mild PwHA. However, the comparison of coagulation potential and bleeding characteristics in PwHA receiving emicizumab (Emi-PwHA) and mild PwHA (PwMHA) remains to be investigated. Here, we examined the clinical and laboratory characteristics in Emi-PwHA and PwMHA. Clinical data of bleeding episodes and coagulation potentials were collected from 64 Emi-PwHA and 15 PwMHA (median FVIII:C 13 IU/dL [IQR 8.5-17.0]). Comprehensive coagulation function was evaluated using Ca 2+-triggered rotational thromboelastometry (ROTEM) and/or ellagic acid/tissue factor-triggered clot waveform analysis (CWA). Furthermore, we compared the features of breakthrough bleeds in two groups.