Hemophilia A

Emicizumab for the Treatment of Acquired Hemophilia A

Emicizumab for the Treatment of Acquired Hemophilia A

In an abstract published in the Journal Blood on January 21, 2021, investigators report on the utility of emicizumab, a bi-specific factor VIII minetic therapeutic antibody that reduces the annualized bleeding rates in congenital hemophilia, in patients with acquired hemophilia A.  

The abstract reports on the utility in 12 patients, 6 men and 6 women with acquired hemophilia A treated with emicizumab.  The median age was 74, with a median initial Factor VIII level less than 1%.  The median inhibitor titer was 22.3 Bethesda units / mL (range, 3–2,000).  Severe bleeding was seen in 8 patients.  Emicizumab was started at 3 mg/kg subcutaneously, weekly for 2 or 3 doses followed by 1.5 mg/kg every 3 weeks to keep the lowest effective factor VIII levels.  For Factor VIII monitoring, chromogenic assays with human and bovine reagents were used.  All 12 patients received immunosuppression with steroids with or without rituximab.  

Activated partial thromboplastin time normalized in 1 to 3 days after the first dose of emicizumab, with Factor VIII levels exceeding 10% after a median of 11 days.  The hemostatic efficacy was obtained and bypassing therapy stopped after a meeting of 1.5 days, with factor VIII levels exceeding 50% as the median, indicating complete remission after 115 days.  Emicizumab was stopped after a median of 31 days. A median of 5 injections, range between 3 and 9, were administered.  No patients died of bleeding or thromboembolism and no breakthrough bleeding was observed after the first dose of emicizumab. 

The authors concluded “emicizumab seems to be an effective hemostatic therapy for acquired hemophilia A, with the advantages of subcutaneous therapy, good hemostatic efficacy, early discharge, and reduction of immunosuppression and adverse events.”