Emicizumab Prophylaxis in Patients With Acquired Hemophilia A During Immunosuppressive Therapy: Real‐World Data From the Spanish Acquired Hemophilia Registry

INTRODUCTION: Acquired hemophilia A (AHA) is a rare bleeding disorder in which immunosuppressive therapy (IST) and hemostatic management remain challenging, particularly in elderly patients. Evidence supporting emicizumab use in AHA under real-world conditions remains limited. AIM: To assess efficacy and safety of emicizumab in providing hemostatic protection until inhibitor eradication. METHODS: We analyse data from the Spanish Acquired Haemophilia Registry, including patients newly diagnosed between 2022 and 2025. Bleeding episodes and red blood cell (RBC) transfusion requirements before and after establishment of effective emicizumab prophylaxis were compared. RESULTS: Twenty patients were included, 85.0% older than 75 years. Only two patients received the accelerated AHA loading regimen used in pivotal AHA studies (6 mg/kg on Day 1, 3 mg/kg on Day 2, followed by 1.5 mg/kg weekly from Day 8). All patients presented with active bleeding at diagnosis. Before emicizumab prophylaxis, all patients experienced bleeding episodes and 70.0% required RBC transfusions. Using Day-7 after the first dose of emicizumab as landmark of efficacy, only 2 patients (10.0%) reported breakthrough bleeding episodes and one patient required RBC transfusion (p = 0.001). Seventeen (85.0%) patients achieved remission after 64 (55-109) days. Two patients died of sepsis during IST. No thrombotic events attributable to emicizumab were observed. CONCLUSION: In this real-world AHA cohort, emicizumab was associated with effective and sustained hemostatic protection, marked reduction in bleeding and RBC transfusion requirements. Prospective studies are needed to define the optimal strategy and to determine whether emicizumab can facilitate individualized timing and intensity of IST.