Real-World Experience with Emicizumab for Hemophilia a from the Physician Perspective Based on Survey Data

Introduction: The safety and effectiveness of emicizumab, a bispecific factor IXa– and factor X–directed antibody approved for routine prophylaxis in adult and pediatric people with hemophilia A (PwHA) with or without factor VIII (FVIII) inhibitors, have been previously evaluated in clinical and real-world studies across various subpopulations since its FDA approval in 2017. However, real-world data for PwHA in settings outside of federally supported hemophilia treatment centers (HTCs) are limited. We aimed to describe the characteristics and treatment experience of US physicians and PwHA receiving emicizumab based on surveys from the latest Adelphi Disease Specific Programme (DSP) data, which includes data collected external to the federally supported HTCs.

Methods: The Adelphi Real World hemophilia A DSP is a cross-sectional study with retrospective collection of data on physicians and male PwHA in the US. Physicians were recruited between July 2023 and April 2024 if they identified their primary specialty as hematologist or hematologist-oncologist (or pediatric equivalent) and treated ≥5 patients with hemophilia A or B per month at the time of the survey. Physicians reported on the demographic characteristics of their patients and other questions related to hemophilia outcomes of interest, including adherence levels, bleed events, healthcare resource utilization and joint issues. Each physician completed record forms for up to 10 consecutively seen PwHA who were male, diagnosed with hemophilia A (with or without inhibitors), had baseline clotting factor <5% and were not currently participating in a clinical trial. Descriptive statistics were used to summarize results.

Results: Overall, 54 physicians participated in the survey, which resulted in completed records for 293 PwHA, of whom 77 were treated with emicizumab. Of the 54 physicians, 63% were hematologist-oncologists, 22% were hematologists and the remainder were pediatric hematologists, pediatric hematologist-oncologists or other specialties. Whereas 50% were practicing in an academic setting, the remaining 50% were in community hospital or office settings. Physicians saw 47% of their patients at HTCs, whereas 39% were seen outside of HTCs and the remaining 14% were seen at both HTCs and non-HTCs. Of the 77 PwHA receiving emicizumab at the time of the survey, the mean (SD) age was 21.7 (11.8) years, the majority (90%) did not have inhibitors, 53% had baseline clotting factor levels <1% and 55% were managed at HTCs. The median [IQR] physician-reported proportion of emicizumab doses taken on time was 100% [90%-100%]. Overall, 49 PwHA had data available for both pre- and post-emicizumab initiation. These 49 PwHA experienced a mean (SD) of 1.3 (1.9) bleeds during the 12 months prior to receiving emicizumab compared with 0.4 (1.1) bleeds during the 12 months after initiation of emicizumab. Of these, 43% had zero bleeds before receiving emicizumab and 80% had zero bleeds after. Of PwHA who experienced bleeds pre-emicizumab initiation, 30% reported the bleed severity as mild, as opposed to moderate or severe, and 27% required hospitalization for factor treatment. In comparison, among PwHA who reported bleeds post-emicizumab initiation, 60% described the bleed severity as mild and 22% required hospitalization. Of the 77 PwHA receiving emicizumab, 82% reported no or mild joint problems at the start of prophylaxis compared with 87% after initiation of emicizumab.

Conclusions: This recent real-world physician survey data showed that PwHA receiving emicizumab experienced few and mild bleeds after initiation of emicizumab. Further, real-world adherence to emicizumab is high, and many PwHA receiving emicizumab have no or mild joint health issues. These results suggest that emicizumab’s effectiveness across HTC and non-HTC settings is consistent with that reported by previous real-world and clinical trial studies.