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Long-term safety and efficacy extension study data of Alprolix® published

Swedish Orphan Biovitrum have annouced that interim results from the B-YOND extension trial, which studies Alprolix® [Coagulation Factor IX (Recombinant), Fc Fusion Protein] in previously treated subjects with severe haemophilia B, were published in the March 2017 issue of Thrombosis and Haemostasis.

The study results reinforce the long-term safety and efficacy of prophylactic treatment with Alprolix over a median duration of more than three years in adults/adolescents and more than a year and a half in children under 12 years of age. The primary outcome measure was development of inhibitors (neutralising antibodies that can interfere with activity of the therapy); no patients treated with Alprolix in the study developed inhibitors.

“The interim data from B-YOND confirm the safety profile of Alprolix, and show that adult, adolescent and paediatric subjects maintained low annual bleed rates with prophylactic dosing of Alprolix every 1-2 weeks,” said John Pasi, MD, PhD, principal investigator of the study, Professor of Haemostasis and Thrombosis at The Royal London Hospital, Barts and the London School of Medicine and Dentistry. “These results come from the longest-term study of an extended half-life therapy for haemophilia B and provide physicians across the globe with important insights and information about the treatment of haemophilia B.”

B-YOND is an ongoing open-label, nonrandomized extension study, and eligible previously-treated patients who completed B-LONG or Kids B-LONG could enrol in one of three treatment groups: weekly prophylaxis, individualized prophylaxis, and modified prophylaxis. An episodic treatment arm is also available only to adult and adolescent participants. At the time of the interim data cut, 116 male subjects (93 from B-LONG and 23 from Kids B-LONG) were enrolled in the study.

“These results confirm the long-term safety and efficacy profile of Alprolix and show that a majority of the participants in the study were able to dose once weekly or less frequently while maintaining adequate protection,” said Maha Radhakrishnan, MD, senior vice president of medical at Bioverativ.

In the individualized prophylaxis treatment group, as of the B-YOND interim data cut, a total of 26 adolescent/adult subjects out of 30 (86.7%) had a dosing interval longer than one week with a median dosing interval of 13.7 days, and paediatric subjects aged 6 to < 12 years had a median dosing interval of 10.0 days. Fifteen of 26 (57.7%) adult/adolescent subjects in the individualised prophylaxis treatment group had a dosing interval of every 14 days or longer.

“Together with Bioverativ, we remain focused on advancing research to better understand the underlying science and potential benefits of Alprolix for people with haemophilia B,” said Krassimir Mitchev, MD, PhD, vice president and medical therapeutic area head of Haemophilia at Sobi.

The overall median annualised bleeding rate (ABR) at the time of the B-YOND interim data cut was 2.3 for adult/adolescent participants in both the weekly and individualized prophylaxis treatment groups, and 2.4 for those in the modified prophylaxis study arm. Participants receiving on-demand therapy, or treatment when a bleeding episode occurred, had a median ABR of 11.3.

Among children under age six (n=9), the median ABR in the weekly prophylaxis group was zero. For children between six and 12 years old, the median ABR was similar in the weekly (2.7; n=10) and individualised (2.4; n=5) prophylaxis groups. The one participant from the 6 to < 12 years cohort who was in the modified prophylaxis group had an ABR of 3.1.

In the B-YOND study as of the interim data cut, Alprolix was well tolerated and adverse events (AEs) were typical of the haemophilia B populations studied. The most common AEs were headache (n=14, 12.1%) and common cold (n=13, 11.2%), and the majority of AEs were considered by the investigator to be unrelated to Alprolix treatment. A total of 39 serious AEs (SAEs) were reported in 23 participants (19.8%) treated with Alprolix. All SAEs were assessed by the investigator as unrelated to Alprolix, with the exception of one SAE of renal colic in an adult/adolescent participant with a medical history of previous clot colic; the event resolved and did not lead to study discontinuation. In the study as of the interim data cut, there were no reports of serious allergic reactions or anaphylaxis associated with Alprolix, no vascular thrombotic events, and no deaths.

The full publication is available online at