Long-Term Safety and Efficacy of Recombinant Coagulation Factor IX Albumin Fusion Protein (rIX-FP) in Previously Treated Pediatric Patients with Hemophilia B: Results from a Phase 3b Extension Study.

Abstract

INTRODUCTION:

 A phase 3b extension study evaluated the long-term safety and efficacy of a recombinant fusion protein-linking coagulation factor IX (FIX) with albumin (rIX-FP) for the routine prophylaxis and on-demand treatment of bleeding in pediatric hemophilia B patients.

METHODS:

 Previously treated patients aged <12 years with moderate to severe hemophilia B enrolled in a 3-year extension study following a phase 3 pivotal study in which they received weekly rIX-FP prophylaxis. In the extension study, they could maintain or extend their prophylaxis interval to every 10 or 14 days if they were well controlled on the 7-day regimen.

RESULTS:

 Compared with their initial regimen, by the end of the study, dosing intervals were the same, extended, and shortened in 16, 4, and 4 patients, respectively. Very low annualized spontaneous bleeding rates (AsBRs) were observed; median AsBR was 0.0 for the 7- and 10-day regimens, and 1.1 for the 14-day regimen. The 7- and 14-day regimens were comparable in preventing spontaneous bleeds; mean (95% confidence interval) difference in AsBR of -1.2 (-2.6 to 0.3) bleeding episodes/year/subject. Overall, 96% of bleeding episodes were successfully treated with one or two injections of rIX-FP. Patients on a 14-day regimen maintained a mean steady-state trough FIX level of >7.2 IU/dL. No patient developed an inhibitor.

CONCLUSION:

 This extension study demonstrated the long-term safety and efficacy of weekly rIX-FP in pediatric patients. Additionally, it showed that adequate bleed protection can be achieved with 10- or 14-day rIX-FP regimens in selected pediatric patients while maintaining safety.

• Authors: Gili Kenet, Hervé Chambost, Christoph Male, Susan Halimeh, Thierry Lambert, Yanyan Li, Wilfried Seifert, Elena Santagostino
• Journal: Thrombosis and haemostasis (Thromb Haemost) Vol. 120 Issue 4 Pg. 599-606 (Apr 2020) ISSN: 2567-689X [Electronic] Germany
• PMID: 32185782 (Publication Type: Clinical Trial, Phase III, Journal Article, Multicenter Study)
• Copyright: Georg Thieme Verlag KG Stuttgart · New York.

Chemical References

• Albumins
• Recombinant Fusion Proteins
• Factor IX

Topics

• Albumins (genetics, therapeutic use)
• Child
• Child, Preschool
• Factor IX (genetics, therapeutic use)
• Hemophilia B (complications, drug therapy)
• Hemorrhage (etiology, prevention & control)
• Humans
• Male
• Recombinant Fusion Proteins (genetics, therapeutic use)
• Time Factors
• Treatment Outcome