Real-World Outcomes of Prophylaxis With rIX-FP in Germany: A Prospective, Non-Interventional Study in Haemophilia B.

INTRODUCTION: Efficacy and safety of albutrepenonacog alfa (rIX-FP) in people with haemophilia B (PwHB) has been previously demonstrated in clinical trials. However, real-world data insights are required.

AIM: To describe real-world effectiveness and tolerability of rIX-FP in PwHB in Germany.

METHODS: Prospective, non-interventional study conducted across 19 sites in Germany. Patients of any age treated with rIX-FP were enrolled between March 2018 and February 2024. Patients were monitored every 3-12 months and followed-up for 3 years or until ≥100 exposure days.

RESULTS: To our knowledge, this is the largest study of factor replacement therapy in PwHB in Germany to date. Of the patients who completed the study (63/73), most (80.8%) had moderate or severe haemophilia B. The mean (standard deviation) duration of observation was 30.5 (8.32) months. For any prophylaxis regimen, the median (range) annualised bleeding rate (ABR) was 0.89 (0.0-9.6) and annualised spontaneous bleeding rate (AsBR) was 0.08 (0.0-5.2). The median ABR was 1.12, 0.68 and 0.13, and the median AsBR was 0.17, 0.00 and 0.06 for those treated with a 7-, 10- or 14-day regimen, respectively. Investigators rated the overall haemostatic effectiveness as 'good' or 'excellent' in 94% of cases (based on the worst assessment). Overall, 82 adverse events in 34 patients were reported, none were considered related to rIX-FP.

CONCLUSION: This multicentre, non-interventional study in Germany demonstrates that rIX-FP prophylaxis is effective and well tolerated in PwHB of all ages in routine clinical practice and reinforces the results of the clinical trials.

© 2026 The Author(s). Haemophilia published by John Wiley & Sons Ltd.

PMID: 42411544