ORPHEE: A Real‐World Study on rIX‐FP Prophylaxis Use in Adolescent/Adult Patients With Hemophilia B

Abstract

ObjectivesTo assess the real‐world efficacy and safety of recombinant factor IX albumin fusion protein (rIX‐FP) in patients with hemophilia B (HB) in France.MethodsData on dosing frequency, weekly consumption, and bleeds before‐and‐after switching to rIX‐FP, were collected from December 2021 to February 2024. Annualized (spontaneous) bleeding rates [A(s)BRs] were calculated only in patients on prophylaxis with a follow‐up ≥ 6 months.ResultsThis interim analysis focused on 77 patients ≥ 12 years; 62 (81%) had severe HB. After switching to rIX‐FP, the infusion interval was 14 (7–14) days. Weekly consumption was 43 (35.5–53) IU/kg. ABRs and AsBRs were 0.5 (0–1.9) and 0 (0–0.7) (n = 63) at 18.2 (12.3–21.9) months of follow‐up. Prophylactic efficacy of rIX‐FP was considered ‘Excellent’/‘Good’ in 65/68 (95%) patients. Among the 43 patients previously treated with rFIXFc, 21 increased the infusion interval from 7 (7–11) days with rFIXFc to 14 (7–14) days with rIX‐FP; 33/43 (77%) reduced weekly factor IX (FIX) consumption from 59.95 (46.35–77.93) to 42.5 (35.88–50.25) IU/kg. Patients maintained good protection against bleeds.ConclusionThis analysis confirmed that switching to rIX‐FP allows for reducing injection frequency and FIX consumption while maintaining good bleed protection.