Real-World Prophylaxis Outcomes with rIX-FP and rFIXFc for Males with Hemophilia B: Pooled Analysis of Medical Chart Data from Germany and Italy

Introduction: The current standard of care for people with severe hemophilia B is prophylaxis with factor IX (FIX) products. This analysis assessed the effectiveness of prophylaxis for people with hemophilia B (PwHB) receiving rIX-FP or rFIXFc prophylaxis in Germany and Italy. Methods: A retrospective, de-identified chart review included PwHB ≥ 12 years with severe/moderate hemophilia B from Germany or Italy, receiving prophylaxis with rIX-FP or rFIXFc for ≥ 12 months. The primary outcome was FIX consumption; the secondary outcomes were dosing interval, annualized bleeding rate (ABR), annualized spontaneous bleeding rate (AsBR), and annualized joint bleeding rate (AjBR). These outcomes were also explored in PwHB with pre- and post-rIX-FP switch data. Results: Of 194 PwHB, 107 and 87 received rIX-FP and rFIXFc prophylaxis, respectively. The mean FIX consumption of rIX-FP was significantly lower compared to rFIXFc (42.4 vs. 65.2 IU/kg/week, p = 0.0001), with mean dosing intervals of 9.5 days (rIX-FP) and 7.9 days (rFIXFc). The mean bleeding rates for rIX-FP versus rFIXFc, respectively, were: ABR 0.7 versus 1.1 (p = 0.6704), AsBR 0.1 versus 0.3 (p = 0.3427), and AjBR 0.3 versus 0.4 (p = 0.5296). Subgroup analyses for PwHB with severe and moderate hemophilia B separately showed similar numerical patterns when comparing these outcomes. In the 18 patients with switch data, a significant reduction in FIX consumption was observed (median 51.7 to 33.3 IU/kg/week, p = 0.0069), and the mean dosing interval was extended (7.2–9.5 days). The ABR (median 1.6–0.0, p = 0.0172; n = 18) and AjBR (median 0.6–0.0, p = 0.0200; n = 14) decreased significantly, while the AsBR decreased but not significantly (median 0.2–0.0, p = 0.1460; n = 14). Conclusion: rIX-FP prophylaxis was associated with reduced FIX consumption versus rFIXFc and offered equally effective or potentially improved bleed protection. Additionally, PwHB who switched to rIX-FP achieved significant decreases in FIX consumption, ABR, and AjBR compared with their prior FIX product.