Sustained Survival Benefit of Emicizumab and Postponed Immunosuppression in Acquired Hemophilia A.

Acquired hemophilia A (AHA) is a severe bleeding disorder caused by neutralizing autoantibodies against coagulation factor VIII (FVIII). Standard treatment involves immunosuppressive therapy (IST), which carries a significant risk of serious infections, the leading cause of death in AHA patients. The GTH-AHA-EMI study investigated the use of emicizumab to prevent bleeding during the first 12 weeks of management while postponing IST. We collected 2-year follow-up data from GTH-AHA-EMI patients (n=47) and compared outcomes to a propensity score (PS)-matched cohort from the GTH-AH 01/2010 study (n=101), in which patients received immediate IST. Outcome measures included overall survival (OS), infection- and bleed-related mortality, and time to complete remission (CR). The study cohorts were well-matched in age, sex, underlying conditions, baseline FVIII activity, inhibitor titer, and performance status. The PS-matched 2-year OS was 82% in the GTH-AHA-EMI cohort versus 63% in GTH-AH 01/2010 (hazard ratio 0.39, 95% confidence interval 0.19-0.80). Infection-related mortality was lower with emicizumab (4% vs. 17%), while bleed-related mortality was similar (4% vs. 3%). Spontaneous remission of AHA occurred in 15% of GTH-AHA-EMI patients. Time to CR estimated by the Kaplan-Meier method was longer with postponed IST in GTH-AHA-EMI (44 vs. 16 weeks), but the estimated proportion of patients achieving CR was similar (76% vs. 66%). In conclusion, emicizumab allowed for postponed IST initiation during early AHA management in the GTH-AHA-EMI study. Delayed IST was safe and effective. Compared to PS-matched historic controls receiving immediate IST but no emicizumab, GTH-AHA-EMI patients had fewer fatal infections and improved OS. NCT04188639.