The US Food and Drug Administration (FDA) has granted Fast Track Designation (FTD) for efanesoctocog alfa, previously known as BIVV001 (rFVIIIFc-VWF-XTEN), in patients with hemophilia A. Efanesoctocog alfa, a novel and investigational factor VIII therapy independent of von Willebrand Factor, is designed to provide near-normal factor activity levels for the majority of the week in a once-weekly prophylactic treatment regimen.
Efanesoctocog alfa was granted orphan drug designation by the US FDA in August 2017 and the European Commission in June 2019. Sanofi and Sobi collaborate on the development and commercialization of efanesoctocog alfa.
Efanesoctocog alfa has the potential to transform factor replacement therapy for patients with hemophilia A and represents a potential new class of factor VIII replacement therapies. The half-life of conventional factor VIII therapy is constrained by the von Willebrand factor’s (VWF) chaperone effect, which is believed to limit the time the factor remains in the body. Efanesoctocog alfa builds on the innovative Fc fusion technology by adding a region of von Willebrand factor and XTEN polypeptides to extend its time in circulation. Efanesoctocog alfa has the potential to provide near-normal bleed protection for the majority of the week, while an increase in half-life may allow reduced dosing frequency of a prophylactic treatment to once a week.
The safety and efficacy of efanesoctocog alfa is currently being evaluated in the ongoing phase 3 XTEND-1 study in previously treated patients =12 years of age (n=150) with severe hemophilia A. XTEND-1 is an open-label, non-randomized interventional study with two parallel assignment arms. Participants in the prophylaxis arm receive a weekly prophylactic 50 IU/kg dose of efanesoctocog alfa for 52 weeks. Participants in the on-demand arm receive BIVV001 (50 IU/kg) on demand for 26 weeks followed by a switch to efanesoctocog alfa weekly prophylaxis for another 26 weeks.
Efanesoctocog alfa is currently under clinical investigation and its safety and efficacy have not been reviewed by any regulatory authority.