Recombinant factor IX-albumin fusion protein (rIX-FP) provides effective hemostasis at dose regimens for up to 21 days in patients with hemophilia B aged ≥18 years and up to 14 days in patients aged <12 years, according to real-world data published in the Journal of Clinical Medicine.

Moreover, rIX-FP has a favorable pharmacokinetic profile and excellent safety and tolerability profile based on the findings of the PROLONG-9FP clinical program. Extended dosing intervals led to high levels of adherence and reduced consumption compared to other factor IX replacement therapies, with potential economic benefit.

“Data from real-world practice are encouraging and reflect the results of the clinical trials,” the authors wrote. rIX-FP is a long-acting factor IX replacement product for the prophylactic treatment of hemophilia B or the perioperative management of children and adults with the disease.

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Factor IX is the blood clotting factor that is deficient in patients with hemophilia B. Even though there are many factor IX replacement products, these can have a high treatment burden due to frequent dosing. Long-acting products can achieve bleed protection even with extended dosing intervals.

The PROLONG-9FP clinical trial program consisted of 5 prospective, open-label, multicenter studies that assessed the safety, efficacy, and pharmacokinetics of rIX-FP in male patients with moderately severe to severe hemophilia B. The trials also included the assessment of extended dosing regimens, management of surgical bleeding, and analysis of long-term outcomes.

The favorable efficacy and consumption of rIX-FP over standard factor IX products and other long-acting products “provide a basis for switching patients to rIX-FP,” the authors said. Extended intervals between rIX-FP doses and lower doses may be tested in future studies to improve individual patients’ options, they said.


Escobar M, Mancuso ME, Hermans C, et al. Idelvion: a comprehensive review of clinical trial and real-world data. J Clin Med. 2022;11(4):1071. doi:10.3390/jcm11041071