Measuring Emicizumab Levels in the Hemostasis Laboratory.

Emicizumab is a bi-specific antibody that in recent years has been introduced in many countries as a prophylactic agent for bleed prevention in cases of severe hemophilia A, and in some cases of moderate HA. It can be used in individuals with HA with and without FVIII inhibitors, because the drug is not a target for these inhibitors. Emicizumab was developed as a fixed weight-based dose and does not normally need laboratory monitoring, but in some circumstances such as a treated HA patient with unexpected bleeding episodes, a laboratory assay is justified. This chapter describes to performance of a one-stage clotting assay to measure emicizumab.