Detailed analysis of anti‐emicizumab antibody decreasing drug efficacy, using plasma samples from a patient with hemophilia A

BackgroundEmicizumab is a humanized bispecific monoclonal antibody that bridges activated factor IX (FIXa) and factor X (FX) to mimic the function of factor VIII (FVIII). It suppresses the bleeding tendency in hemophilia A patients with or without FVIII inhibitors. A case of an adult FVIII inhibitor‐positive hemophilia A patient in whom treatment with emicizumab was discontinued owing to the repeated bleeding events and prolonged activated...