PB0002 - Emicizumab for the treatment of acquired hemophilia A: an update of the Vienna experience

Background: Acquired hemophilia A (AHA) is a severe bleeding disorder caused by inhibiting autoantibodies to FVIII. For hemostatic treatment bypassing agents, human or porcine FVIII are currently standard of care. Recently, we reported on the advantages of emicizumab, a bispecific, FVIII-mimetic therapeutic antibody, in patients with AHA. Good hemostatic activity, weekly (or longer) subcutaneous injections, early discharge, and reduced need for immunosuppression improve patients management.

Aims: Meanwhile, emicizumab has become standard of care for AHA in our center. This is an update on our experience.

Methods: Emicizumab was given at 3 mg/kg sc. weekly for 4 weeks, followed by 1.5 mg/kg in 2-4 weeks intervals. For FVIII monitoring chromogenic assays with human and bovine reagents were used.

Results: Up to now, we have treated 20 patients with AHA according to this strategy, 11 male, 9 female, median age 79 yrs (range 51-87). The initial FVIII activity was < 1%, the max. inhibitor 69 BU/mL (3-2300). Most patients had severe bleeding, requiring RBC transfusions and therapy with rhFVIIa prior to emicizumab.
APTT normalized 1-3 days after the first dose, hemostatic efficacy was obtained and bypassing therapy was stopped after 4 (0-9) days. FVIII exceeded 50%, indicating complete remission, after 115 days (median). All patients received immunosuppression with steroids and rituximab. 18 patients were discharged 2 weeks after the first emicizumab injection, and followed and treated every 3 weeks until complete remission. No breakthrough bleeding was observed. In 2 patients, all treatment was terminated within a few days because of advanced comorbidities, both patients expired.

Conclusion(s): In conclusion, our data confirm the advantageous properties of emicizumab for the management of AHA. Special attention is needed on the use of appropriate lab assays, the recognition of remission, and to avoid the concomitant use of APCC. A clinical trial on emicizumab for AHA is currently ongoing.