Utilization of Emicizumab in Acquired Factor VIII Deficiency

BACKGROUND Acquired hemophilia A (AHA) is a rare autoimmune disease caused by immunoglobulins that bind and inactive factor VIII, thereby predisposing to life-threatening bleeding. Bleeding is typically stabilized by utilizing bypassing agents, such as recombinant factor VIIa (rVIIa). Select case reports have demonstrated the success of alternative prophylaxis for clearance of factor VIII inhibitors through the use of emicizumab, a current FDA approved medication for treatment of congenital hemophilia A. In this case report we present the efficacy of utilizing emicizumab as a prophylactic agent in a patient that was unable to tolerate first-line therapy for prophylaxis. CASE REPORT A 91-year-old male presented for ongoing hematuria for 5 weeks with prior workup unrevealing. He was given a day's course of recombinant factor VIIa to stabilize his bleeding and was started on cyclophosphamide and prednisone after a revealing hematological workup including activated partial thromboplastin time (aPTT) >100 seconds and factor VIII inhibitor level of 44 BU/mL. He continued to require VIIa infusions to control his bleeding and was started on emicizumab once stabilized. His bleeding remained controlled and his inhibitor decreased after 6 months of therapy with repeat factor VIII inhibitor level of 1.9 BU/mL. CONCLUSIONS The success of utilizing emicizumab for bleeding prophylaxis in AHA is demonstrated by this patient's resolution of bleeding. The high frequency of dosing and higher risk for thrombosis with factor VIIa, in conjunction with our patient's medical history and ease of administration, make emicizumab an ideal agent for bleeding prophylaxis while awaiting clearance of factor VIII inhibitors.