Efficacy and Safety Results of Prolong-9FP Clinical Program of Recombinant Fusion Protein Linking Coagulation Factor IX with Albumin (rIX-FP) in Previously Treated Patients with Hemophilia B

A fusion protein genetically linking recombinant human coagulation FIX with recombinant human albumin (rIX-FP) has been developed with an improved PK profile, thus improving hemophilia B treatment by allowing less frequent dosing.

Two Phase 3 studies (CSL654-3001 and CSL654-3002) were completed. CSL654-3001 study evaluated safety and efficacy of rIX-FP for prophylaxis treatment (PT) of every 7-, 10- and 14-day and on-demand (ODT) of bleeding episodes in 63 previously treated patients (PTP), 12-61 years of age with hemophilia B (FIX ≤ 2%).  Subjects in the on-demand arm received only ODT for 6 months and then switched to every 7-day PT. Subjects in the prophylaxis arm received every 7-day PT, and eligible subjects switched to every 10- or 14-day PT for approximately 12-18 months . Annualized spontaneous bleeding rates (AsBR) were compared between ODT and PT periods (in on-demand arm), and between 7-day PT and 10- or 14-day PT (in prophylaxis arm).  CSL654-3002 study evaluated safety and efficacy of rIX-FP for weekly prophylaxis regimen in 27 previously treated patients younger than 12 years with hemophilia B (FIX ≤ 2%) for approximately 12 months.  Annualized spontaneous bleeding rates (AsBR) were calculated.  The median annualized spontaneous bleeding rate were all 0.00 for all treatment interval (7-day, 10-day or 14-day) and in both studies age groups (1-11 years and 12-65 years) during the two completed phase 3 studies. 

Seventy-six subjects from both studies continued their prophylaxis regimen in the on-going extension study.  In addition, subjects (including children), switched to longer treatment intervals of 10-day, 3 times per month or 14-day or lowered their weekly prophylaxis dose.  Nine subjects switched to 21-day treatment interval with 100 IU/kg rIX-FP.  As of 28 July 2015, at least 50 subjects (PTP) had achieved 100 EDs without developing an inhibitor to FIX or antibodies to rIX-FP.  The long term safety and efficacy of rIX-FP  will be presented.  This presentation includes the new information regarding the change to longer than 7-day treatment regimens in the extension study, among those subjects (1-61 years of age) that previously participated in the lead in studies.

Conclusion: The Prolong – 9FP clinical program demonstrated the clinical efficacy of rIX-FP for routine prophylaxis every 7-, 10- and 14-day treatment intervals.  Routine prophylaxis once every 21 days may be effective in preventing bleeding episodes in a selected patient population. In addition, rIX-FP demonstrated favorable long-term safety and tolerability.