Real-world treatment patterns for Hemophilia A since the launch of emicizumab in the US

Abstract Introduction: Emicizumab is a recombinant, humanized, bispecific, monoclonal antibody that has become the standard of care in hemophilia A prophylaxis. Adoption of emicizumab as standard of care was likely supported by its subcutaneous administration and consistent pharmacokinetics compared with FVIII. Updated real-world insights on treatment patterns since the US launch of emicizumab in 2017 are needed to support clinical decision-making and highlight potential unmet needs. The objective of this study was to describe prophylactic treatment patterns among people with hemophilia A (PwHA) in the US receiving newer therapies on the market since the launch of emicizumab in the US. Methods: This retrospective, observational cohort study used real-world US adjudicated health plan claims data from IQVIA PharMetrics® Plus. PwHA were included if they had ≥1 claim for emicizumab or efanesoctocog alfa between November 1, 2017, and September 30, 2024. Individuals were required to have a diagnosis for hemophilia A and were excluded if they had diagnoses for any other rare bleeding disorders. The index date was the date of the first fill of emicizumab or efanesoctocog alfa, and the index drug was defined as the treatment identified on the index date. Continuous pharmacy and medical benefits were required during the 6 months prior to and a minimum of 2 months after the index date. The follow-up period started at the index date until the end of enrollment or the end of the study period, whichever occurred first. The primary study outcome was the proportion of PwHA who switched fills between emicizumab and efanesoctocog alfa during the follow-up period. The sequence of treatments and time to switching treatments were also described. Results: Among 698 PwHA with emicizumab as their index drug, 13 (2%) had ≥1 claim for efanesoctocog alfa over a median follow-up of 23 months. Among the 13 PwHA who switched from emicizumab to efanesoctocog alfa, 4 (31%) switched back to emicizumab. The mean (SD) time between the first emicizumab fill to an efanesoctocog alfa fill was 11 (4) months after the approval of efanesoctocog alfa in the US. Among 53 PwHA with efanesoctocog alfa as the index drug, 2 (4%) had ≥1 claim for emicizumab over a median follow-up of 6 months. PwHA with efanesoctocog alfa as the index drug were older (mean [SD] age, 31 [20] vs 22 [17] years) and had higher rates of prior treatment with factor VIII therapies or bypassing agents before their index drug (60% vs 50%)than PwHA with emicizumab as the index drug. For both cohorts, the majority were male (98%) and had commercial insurance (76%). Conclusions: Among PwHA receiving newer therapies in the real-world setting, switching fills between emicizumab and efanesoctocog alfa was infrequent (2% vs 4%). The majority of PwHA initiated and persisted with emicizumab prophylaxis, supporting its real-world effectiveness as the standard of care.