Coagulation Factor IX (Recombinant), Albumin Fusion Protein (Albutrepenonacog Alfa; Idelvion®): A Review of Its Use in Haemophilia B.

Albutrepenonacog alfa (Idelvion®), a fusion protein that genetically fuses recombinant factor IX (rFIX) with recombinant human albumin (rAlbumin), is indicated in the treatment of haemophilia B. This narrative review discusses the pharmacological properties and clinical data related to the use of this novel fusion protein, hereafter referred to as rIX-FP. The fusion of rFIX to rAlbumin prolongs the elimination half-life of rIX-FP in the circulation, allowing routine prophylaxis to be administered once every 7-14 days. In the pivotal phase 3 clinical trials in previously treated patients with moderately severe to severe haemophilia B, routine rIX-FP prophylaxis (administered once every 7 days in children, and once every 7-14 days in adolescents and adults) was associated with low annualized spontaneous, total and joint bleeding rates, and was associated with significantly fewer bleeding episodes than on-demand treatment. rIX-FP was also effective in controlling bleeding episodes when used as on-demand treatment and in maintaining haemostasis in the perioperative setting. rIX-FP was well tolerated in the clinical trials, with no reports of inhibitor development. In conclusion, rIX-FP provides an effective, well-tolerated option for the treatment and management of haemophilia B that, by virtue of its extended half-life, is less burdensome than conventional FIX products.