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Long-term safety and efficacy of extended-interval prophylaxis with recombinant factor IX Fc fusion protein (rFIXFc) in subjects with haemophilia B

Pasi, K.J., Fischer, K., Ragni, M., Nolan, B., Perry, D.J., Kulkarni, R., Ozelo, M., Mahlangu, J., Shapiro, A.D., Baker, R.I., Bennett, C.M., Barnes, C., Oldenburg, J., Matsushita, T., Yuan, H., Ramirez-Santiago, A., Pierce, G.F., Allen, G. and Mei, B. (2016) Long-term safety and efficacy of extended-interval prophylaxis with recombinant factor IX Fc fusion protein (rFIXFc) in subjects with haemophilia B. Thrombosis and Haemostasis, 117 (3). pp. 508-518.

Link to Published Version: http://dx.doi.org/10.1160/TH16-05-0398
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Abstract

The safety, efficacy, and prolonged half-life of recombinant factor IX Fc fusion protein (rFIXFc) were demonstrated in the Phase 3 B-LONG (adults/adolescents ≥12 years) and Kids B-LONG (children <12 years) studies of subjects with haemophilia B (≤2 IU/dl). Here, we report interim, long-term safety and efficacy data from B-YOND, the rFIXFc extension study. Eligible subjects who completed B-LONG or Kids B-LONG could enrol in B-YOND. There were four treatment groups: weekly prophylaxis (20–100 IU/kg every 7 days), individualised prophylaxis (100 IU/kg every 8–16 days), modified prophylaxis (further dosing personalisation to optimise prophylaxis), and episodic (on-demand) treatment. Subjects could change treatment groups at any point. Primary endpoint was inhibitor development. One hundred sixteen subjects enrolled in B-YOND. From the start of the parent studies to the B-YOND interim data cut, median duration of rFIXFc treatment was 39.5 months and 21.9 months among adults/adolescents and children, respectively; 68/93 (73.1 %) adults/adolescents and 9/23 (39.1 %) children had ≥100 cumulative rFIXFc exposure days. No inhibitors were observed. Median annualised bleeding rates (ABRs) were low in all prophylaxis regimens: weekly (≥12 years: 2.3; <6 years: 0.0; 6 to <12 years: 2.7), individualised (≥12 years: 2.3; 6 to <12 years: 2.4), and modified (≥12 years: 2.4). One or two infusions were sufficient to control 97 % (adults/adolescents) and 95 % (children) of bleeding episodes. Interim data from B-YOND are consistent with data from B-LONG and Kids B-LONG, and confirm the long-term safety of rFIXFc, absence of inhibitors, and maintenance of low ABRs with prophylactic dosing every 1 to 2 weeks.

Item Type: Journal Article
Murdoch Affiliation: Institute for Immunology and Infectious Diseases
Publisher: Schattauer
Copyright: © 2016 Schattauer Publishers
URI: http://researchrepository.murdoch.edu.au/id/eprint/35971
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