Emicizumab in Acquired Haemophilia A: A Single Haemophilia Comprehensive Care Centre Experience in the United Kingdom

Acquired haemophilia A (AHA) is an autoimmune bleeding disorder mediated by the production of autoantibody inhibitors against factor VIII (FVIII), resulting in a bleeding phenotype. The standard treatment of AHA includes immunosuppressive therapy for inhibitor eradication, haemostatic treatment with FVIII bypassing agents and treatment of underlying causes. Emicizumab is a bispecific monoclonal antibody that restores the function of missing activated FVIII by bridging FIXa and FX. Emicizumab is successfully used for prophylaxis of bleeding in congenital haemophilia A patients with or without FVIII inhibitors; however, it is not licensed for AHA treatment in the United Kingdom. We summarise our single-centre experience of the use of emicizumab for the treatment of AHA in 10 patients in the United Kingdom. Emicizumab was started at a dose of 3 mg/kg weekly with a change to fortnightly after the fourth dose. Eight patients received a combination of corticosteroids, emicizumab and rituximab; the remaining two, emicizumab and corticosteroids. In seven patients, emicizumab was stopped after achievement of an FVIII response and haemostasis following a median of 7 doses (3-53). In one patient, the treatment with emicizumab was complicated by the development of microangiopathic haemolytic anaemia. Three patients died, and in two of them, the death was associated with bleeding.