rIX-FP Protein Exhibits Prolonged Circulating Half-Life in Hemophilia B Patients

An investigational recombinant “fusion protein” linking coagulation factor IX and human albumin was developed by CSL Behring to facilitate extended intravascular half-life of the clotting protein and thereby enable less frequent factor IX (FIX) dosing by persons with hemophilia B. A multinational team evaluated the safety and pharmacokinetics of 25, 50 and 75 IU/kg single infusions of this investigational agent (rIX-FP) in 25 previously treated subjects with hemophilia B (≤2 IU/dL).

No allergic reactions or inhibitors were observed in any subject. Four mild, possibly treatment-related adverse events were reported. In the 50 IU/kg cohort comprising 13 subjects, the mean half-life of rIX-FP was 92 hours, more than five times longer than the subjects’ previous FIX product. After 25 or 50 IU/kg rIX-FP administration, the baseline-corrected mean FIX activity remained elevated at day seven (7.4 IU/dL and 13.4 IU/dL, respectively) and day 14 (2.5 IU/dL and 5.5 IU/dL,respectively).

The investigators concluded that these and other reported results demonstrate both the safety and improved pharmacokinetics of rIX-FP, “indicating this new product with extended half-life as possibly able to control and prevent bleeding with less frequent injection.”