B-YOND long term results for Alprolix confirms safety and efficacy in haemophilia B.- Swedish Orphan Biovitrium + Bioverativ.

Swedish Orphan Biovitrium and Bioverativ announced the final results of B-YOND, the most comprehensive long-term study of extended half-life factor therapies in haemophilia B. The data confirms the established safety and sustained efficacy of Alprolix (eftrenonacog alfa) over four years of treatment in previously treated adult, adolescent, and paediatric patients with severe haemophilia B.

No inhibitors were observed in subjects enrolled in the study and the overall safety profile was consistent with the pivotal phase III studies. Inhibitor development has been observed with eftrenonacog alfa post market. B-YOND is an open-label, non-randomised, multi-year extension study for people who completed the pivotal, phase III B-LONG or Kids B-LONG studies.

Key findings include the fact that for subjects on prophylactic treatment, spontaneous joint annualised bleed rates (ABRs) remained low throughout the study across all age groups, especially related to joint and spontaneous joint bleeds. In adult and adolescent subjects following a prophylactic regimen with eftrenonacog alfa, joint and spontaneous joint median ABRs were below 1.58 and below 0.38, respectively. In study participants less than 12 years on prophylactic treatment joint and spontaneous joint median ABRs were below 0.85 and zero, respectively. Data showed 85 per cent of adult and 93 per cent of paediatric subjects either lengthened or experienced no change in dosing intervals during the extension study. Eftrenonacog alfa provides flexible dosing while maintaining consistently low bleeding rates with extended interval dosing up to 14 days. The B-YOND study reflects real world use of eftrenonacog alfa with flexible dosing and adjustments based on individualised preference and clinical needs. These results were presented at the 60th Annual Meeting of the American Society of Hematology (ASH).