Patient characteristics, treatment patterns, and bleeding in people with Hemophilia A without inhibitors initiating efanesoctocog alfa in the US: An administrative claims analysis

Abstract Background: Hemophilia A is a rare genetic disorder causing spontaneous bleeding and joint damage. Efanesoctocog alfa (Efa) is a first-in-class high-sustained recombinant factor VIII (FVIII) replacement therapy approved in the United States (US) in February 2023 for prophylaxis, perioperative management, and on-demand treatment of bleeds in adults and children with hemophilia A. However, real-world data on the use of Efa are limited. Aim: To describe patient characteristics, treatment patterns, and annualized bleed rates (ABRs) among people with hemophilia (PwHA) without inhibitors receiving prophylactic Efa in routine clinical practice. Methods: This retrospective observational cohort study used US administrative closed claims to identify PwHA without inhibitors initiating prophylactic Efa. Index date was the first claim for Efa between February 22, 2023, and January 01, 2024, that met the criteria for prophylactic use. Patients were required to have ≥180 days of continuous health plan enrollment prior and post index date. A 180-day pre-index washout period was applied to exclude patients with prior Efa use who did not meet the criteria for prophylactic use of Efa. Demographics were assessed at index; clinical comorbidities, prior hemophilia therapies, and bleeds were evaluated during the 180-day pre-index period. Treatment patterns were assessed from index through the end of follow-up and ABRs were assessed from 1 day after index through the end of the follow-up period, death, disenrollment, or end of Efa therapy, whichever occurred first. Treatment patterns were described for all patients, and bleed rates were assessed for those with continuous Efa use for ≥180 days post-index. Results: Eighty PwHA initiated prophylactic Efa. The mean (SD) age of the study population (N=80) was 26.6 (14.7) years, with 43.8% of patients aged 18–39 years. Patients were predominantly male (96.3%), White (46.3%), and had Medicaid coverage (61.3%). Geographical distribution of the patients was comparable across the South (31.3%), Midwest (28.8%), and West (28.8%) regions of the US. Demographics were similar across 47 patients who had ≥180 days of continuous Efa therapy post index. The top comorbidities were pain (33.8%), arthritis (30.0%), obesity (11.3%), anxiety (11.3%), and hypertension (8.8%). The mean (SD) Charlson Comorbidity Index score among all patients was 0.49 (1.28). Within the 180-day pre-index period, 81.3% of patients received any prophylaxis (FVIII or emicizumab), 5% used on-demand FVIII therapy only, and 13.7% patients were not treated with FVIII or emicizumab. The most commonly used products as on-demand or prophylactic prior to index were efmoroctocog alfa (30.0%), octocog alfa (17.5%), emicizumab (15.0%), and rurioctocog alfa pegol (11.3%). The most common last prophylactic treatment product classes used prior to index were extended half-life (EHL) (46.3%), followed by standard half-life (SHL) (18.8%), and emicizumab (10%). Among the 80 patients followed up for an average of 255 days, the average proportion of days covered by Efa therapy was 80%. On average, each patient had 10 (4.7) claims for Efa, with an average duration of treatment of 205 (83) days. Fifteen patients discontinued Efa, of whom 9 ended treatment, 3 re-initiated Efa (defined as a new claim for Efa after a gap of >60 days), and 3 switched to another hemophilia A therapy. In the 180-day baseline period prior to index, 6 out of 47 patients receiving Efa continuously for ≥180 days post-index had a total of 8 bleeds (7 non-traumatic and 1 traumatic). The mean (SD) baseline ABR among these 47 patients was 0.35 (1.06) for all bleeds including traumatic bleeds, 0.30 (1.03) for non-traumatic bleeds, and 0.04 (0.30) for traumatic bleeds. Two of 8 bleed events were joint bleeds, with a mean (SD) ABR of 0.09 (0.41). Over an average (SD) follow-up period of 272 (64) days, 3 out of 47 (6.4%) patients had a total of 3 non-traumatic bleeds, with a mean (SD) ABR of 0.09 (0.35). Of these, 2 bleeds were joint-related (mean [SD] ABR=0.06 [0.29]), and 1 was a gastrointestinal bleed (mean [SD] ABR=0.03 [0.21]). Conclusions: This retrospective claims analysis showed that bleed rates among PwHA receiving Efa were low, consistent with outcomes observed in clinical trials. Most patients transitioning to Efa were previously treated with EHLs. Majority of patients continued treatment during the follow-up period, with relatively low switching or discontinuation of treatment.