Biogen + SOBI announce interim results from B-YOND study of Alprolix for prophylaxis of haemophilia B

New clinical data support the long-term safety and efficacy of Alprolix [Coagulation Factor IX (Recombinant), Fc Fusion Protein], from Biogen + SOBI, in people with severe haemophilia B treated for up to two years. Participants in the Phase III, open-label extension study, B-YOND, maintained low bleeding rates with 1–2 week prophylaxis regimens, according to data from an interim analysis. Investigators presented these interim results for the first time at the 67th Annual Meeting of the National Hemophilia Foundation (NHF) in Dallas, USA.

B-YOND is a multi-year study for people with severe haemophilia B who completed the Phase III pivotal B-LONG or Kids B-LONG studies. In this interim analysis, the median time on Alprolix during B-YOND was 27.6 months for adults and adolescents (n=93), and 47.7 weeks for children under age 12 (n=23). The study’s primary endpoint is inhibitor development, and no inhibitors have been reported to-date. There were three prophylactic dosing options for adult, adolescent, and paediatric participants in the B-YOND trial – weekly, individualized, and modified prophylaxis. Alprolix is a recombinant clotting factor IX therapy designed to have prolonged circulation in the body. According to the interim analysis, adults and adolescents treated prophylactically maintained protection against bleeding episodes with infusions every 1–2 weeks. These participants had overall median annualised bleeding rates (ABR) of 2.28/yr for weekly prophylaxis (20–100 IU/kg of Alprolix every seven days), 2.25/yr for individualised prophylaxis (100 IU/Kg of Alprolix every 8 to 16 days, or twice-monthly) and 2.42/yr for modified prophylaxis (personalised dosing if optimal prophylaxis could not otherwise be achieved). In contrast, people receiving on-demand therapy, or treatment when a bleeding episode occurred, had a median ABR of 11.27/yr. The median overall ABR was zero for children under age six who received weekly prophylaxis (n=9). For children between six to 12 years old, median overall ABRs were 2.65/yr (n=10), 2.37/yr (n=5) and 3.13/yr (n=1) in the weekly, individualised and modified prophylaxis regimens, respectively. In each age group, the median average weekly dose for participants previously on prophylaxis was similar for individuals in the weekly and individualised treatment arms.