The Role of Emicizumab in Patients with Acquired Hemophilia A

Acquired hemophilia A (AHA) is a bleeding disorder caused by autoantibodies against coagulation factor VIII (FVIII). Emicizumab is a FVIII mimetic antibody used in the treatment of inherited hemophilia A that could potentially be used in AHA to achieve hemostasis and shorten hospital stay while reducing bypass therapies. We report on 12 cases of AHA patients treated with emicizumab in an academic center between January 2020 and June 2024. There were 5 male and 7 female patients, with median (interquartile range [IQR]) age and maximum inhibitor titer of 73 (60-76) years and 138 (36.75 -164.25) BU/mL, respectively. Patients had an initial FVIII activity level of <10 and <1 on chromogenic and blood clot-based assays, respectively. Ten patients were started on emicizumab while admitted inpatient, while 2 were started outpatient. The initial emicizumab dose was 3 mg/kg for 8 patients and 1.5 mg/kg for 4 patients; all patients then continued therapy with emicizumab 1.5 mg/kg every other week starting on day 8 and received immunosuppression with steroids and rituximab. Patients received a median (IQR) of 5 (2-6.5) emicizumab injections. FVIII activity recovered past 20% and 50% after a median (IQR) of 28 (13-64.5) and 52 (13-170) days after emicizumab initiation, respectively. Patients who began emicizumab therapy inpatient required a median (IQR) of 8 (6-9) days of bypass therapy and stopped bypass therapy 4 (1.75-6.25) days after emicizumab initiation. Furthermore, these patients were hospitalized for a median (IQR) of 10 (6.5-18.75) days and discharged 3 (2-6) days after starting emicizumab. One patient developed deep vein thrombosis and acute pulmonary thromboembolism while on emicizumab and was subsequently treated with anticoagulation. Three other patients died but unrelated to thromboembolism or bleeding complications. In conclusion, emicizumab appears to be an effective treatment in attaining hemostasis and reducing need of bypass therapy in patients with AHA. Emicizumab use in AHA may warrant monitoring for thromboembolic complications, and further study is needed to determine whether immunosuppression can be avoided.

No relevant conflicts of interest to declare.

Emicizumab is a coagulation factor VIII mimetic antibody used in the treatment of inherited hemophilia A that could potentially be used in the treatment of acquired hemophilia A to achieve hemostasis.