In vitro combined haemostatic efficacy of emicizumab and extended half-life factor VIII compounds.

Abstract

Introduction: Early prophylaxis is the gold standard of care for severe haemophilia. The development of subcutaneous Factor VIII (FVIII) mimetics, such as emicizumab, has significantly reduced the disease burden and improved protection against bleeding episodes. Despite its benefits, emicizumab does not fully normalize haemostasis, requiring additional FVIII treatment for surgical procedures and management of breakthrough bleeding. In these cases, extended or ultra-extended half-life FVIII products are most commonly used. However, laboratory monitoring of these combinations can be challenging.

Aim: This study investigates the in vitro combined haemostatic activity of emicizumab with efmoroctocog alfa and efanesoctocog alfa using a thrombin generation assay (TGA).

Results and conclusion: TGA can be used to monitor combined treatment with emicizumab and either efmoroctocog alfa or efanesoctocog alfa, which is not possible with currently available FVIII reagents for the latter. As expected, there is no synergistic effect between the mimetic and FVIII at therapeutical doses. Both efmoroctocog alfa and efanesoctocog alfa show similar in vitro procoagulant activity in terms of thrombin generation.