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Sobi announces new results from Phase 3 clinical trial


Swedish Orphan Biovitrum (Sobi) and Bioverativ have announced that results from the Kids B-LONG Phase 3 clinical trial, which studied Alprolix in previously-treated children with severe haemophilia B.

The primary outcome measure of the trial was development of inhibitors, and no patients treated with Alprolix in the study developed inhibitors. Treatment was generally well tolerated and resulted in low bleeding rates in participants, most of whom remained on once-weekly dosing during the study. The manuscript, entitled “Recombinant Factor IX Fc Fusion Protein in Children with Haemophilia B (Kids B-LONG): Results from a Multicentre, Non-Randomised Phase 3 Study,” was published in the February 2017 issue of The Lancet Haematology.

“The Medical and Scientific Advisory Council of the National Hemophilia Foundation recommends that prophylaxis be considered the optimal treatment regimen for people with severe haemophilia B, and be initiated early based on the body of evidence demonstrating improved long-term clinical outcomes,” said Roshni Kulkarni, MD, Department of Paediatrics and Human Development, Michigan State University, East Lansing, Michigan, United States, and investigator in the study. “To date, Kids B-LONG is the largest study to evaluate the safety and efficacy of extended half-life factor IX therapy in children with haemophilia B, and the study’s results align with those in studies of Alprolix in adults and adolescents.”


Kids B-LONG investigated the safety, efficacy and pharmacokinetics (measurement of the presence of the drug in a person’s body over time) of Alprolix in previously treated children under the age of 12 with severe haemophilia B (n=30). The primary outcome measure was development of inhibitors (neutralizing antibodies that can interfere with the activity of the therapy). Secondary outcomes included pharmacokinetics, annualized bleeding rate (ABR), and the number of injections required to resolve a bleed.

In this study, no participants developed inhibitors to Alprolix. Alprolix was well tolerated and adverse events (AEs) observed were typical of the paediatric haemophilia B population. The most common AEs were common cold (n=7, 23%) and fall (n=6, 20%). Four participants experienced serious AEs during the study, all of which were assessed as unrelated to Alprolix by the investigators. In the study, there were no reports of anaphylaxis or serious hypersensitivity reactions to Alprolix, no vascular thrombotic events, and no deaths.

Children (n=30) treated prophylactically with Alprolix had a median ABR of 2.0 overall and zero spontaneous joint bleeds. Of all patients treated, 10 of 30 (33%) experienced no bleeding episodes, and 19 of 30 (63%) reported no joint bleeding on-study. Overall, 92 per cent of bleeding episodes were controlled by one or two injections of Alprolix. Following a switch to Alprolix therapy, 80 per cent of children extended their dosing interval compared to previous treatment, and nearly all remained on once-weekly prophylactic dosing throughout the study.

“These data in children reaffirm the well-characterized efficacy and safety profile of Alprolix as demonstrated in studies of adults and adolescents with haemophilia B, and they build on the robust real-world experience of Alprolix over more than two years,” said Maha Radhakrishnan, MD, senior vice president of medical at Bioverativ. “Together with Sobi, we are committed to advancing the care of people with haemophilia around the world.”

“Through Fc fusion technology, Alprolix uses the body’s natural pathway to prolong the time the therapy remains in the body,” said Krassimir Mitchev, MD, PhD, vice president and medical therapeutic area head of haemophilia at Sobi. “Along with Bioverativ, we are dedicated to furthering the study of real-world clinical use of Alprolix and continuing to explore the potential of Fc fusion technology to address the significant unmet needs that remain in haemophilia.”