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First patient dosed in Sobi’s XTEND-Kids study

Ravi Rao

Swedish Orphan Biovitrum has announced that the first patient has been dosed in the phase 3, open-label, interventional XTEND-Kids study of efanesoctocog alfa (BIVV001) in paediatric subjects with severe haemophilia A.

The XTEND-Kids study is designed to investigate the efficacy, safety and pharmacokinetics of efanesoctocog alfa as once-weekly prophylaxis in approximtately 65 previously treated patients ≤12 years of age. Duration of treatment in the study is 52 weeks. Efanesoctocog alfa is being developed and will be commericalized in partnership with Sanofi.

The potential to advance the treatment of people with haemophilia A

Factor VIII (FVIII) replacement therapy as a single agent has been shown in clinical studies and real-world experience to control and prevent bleeding effectively in a variety of settings including surgery1. Efanesoctocog alfa represents a potential new class of FVIII replacement therapy with high sustained factor levels, and the first recombinant FVIII therapy that is designed to be von Willebrand factor (VWF) independent, which extends half-life. It is currently in clinical development and has the potential to offer extended protection with once weekly dosing2, thus addressing an unmet need for people living with severe haemophilia A.


“Efanesoctocog alfa has the potential to advance the treatment of people with haemophilia A,” says Ravi Rao, Head of R&D and Chief Medical Officer at Sobi. “The initiation of the phase 3 development in the paediatric population is a demonstration of Sobi’s continued commitment to enable higher standards for people living with haemophilia A.”

Efanesoctocog alfa is currently in phase 3 clinical trials and was granted Fast Track designation by the US Food and Drug Administration (FDA) in February 2021. It was also granted Orphan Drug designation by both the US FDA in August 2017 and the European Commission in June 2019.


XTEND-Kids is an open-label, non-randomised interventional, single-arm study. Participants will receive a weekly prophylactic dose of efanesoctocog alfa for 52 weeks. XTEND-Kids will evaluate efficacy, safety and pharmacokinetics in approximately 65 previously treated patients ≤12 years of age with severe haemophilia A.

Photo of Ravi Rao: Sobi