PO06 - Emicizumab for the treatment of acquired hemophilia A in a patient with terminal prostate cancer.

Background: Acquired hemophilia A (AHA) is a rare blood coagulation disorder caused by autoreactive immunoglobulin against factor VIII (FVIII inhibitor). Although the etiology is unknown in half of cases, some cases are associated with malignancies. The standard of care is the combination of immunosuppressive and hemostatic therapies. Prednisolone alone or in combination with cyclophosphamide is the first-line immunosuppressive therapy. To control active bleeding, bypassing agents are recommended. Recently, emicizumab was approved for prophylactic use. Emicizumab, a bispecific antibody, mimics the action of activated FVIII and has proved effective in managing patients with AHA. We report the use of emicizumab in an AHA patient with terminal prostate cancer.

Aims: To evaluate the efficacy of emicizumab in an AHA patient with cancer.

Methods: We retrospectively reviewed the medical record.

Results: An 81-year-old man presented with hematuria. He was previously diagnosed with terminal prostate cancer, hypertension, diabetes mellitus and stage 4 chronic kidney disease. Low-dose aspirin antiplatelet therapy had been prescribed since a cerebral infarction 11 years previously. The laboratory findings on admission included a hemoglobin level of 5.0 g/dL and a platelet count of 221,000 /μL. Although his prothrombin time, fibrinogen and D-dimer levels were normal, his activated partial prothrombin time was prolonged (145 s). Additional blood coagulation tests confirmed the diagnosis of AHA with FVIII activity < 1% and an FVIII inhibitor titer of 23.3 Bethesda units. Computer tomography revealed a subcutaneous hematoma in the right chest wall. Prednisolone was immediately administered with simultaneous red blood cell transfusions, and emicizumab was introduced to control bleeding. Although his FVIII inhibitor titer was continuously increasing, he was discharged and received once-weekly emicizumab therapy without serious bleeding.

Conclusion(s): Although the underlying cause could not be treated and the FVIII inhibitor titer remained high, emicizumab controlled bleeding and maintained quality of life in a terminal cancer patient with AHA.