Efanesoctocog Alfa Earns Breakthrough Therapy Status

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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The U.S. Food and Drug Administration (FDA) has granted breakthrough therapy designation to efanesoctocog alfa, an experimental replacement therapy for hemophilia A designed for once-weekly dosing.

This designation is given by the FDA to help speed the development and review of treatments for serious or life-threatening conditions. Specifically, breakthrough therapies are treatments that have shown early clinical evidence of superiority compared with existing methods of care.

“This designation supports the innovation of efanesoctocog alfa and acknowledges its potential to fulfill an unmet medical need for people living with hemophilia A,” Anders Ullman, MD, PhD, said in a press release. Anders is head of research and development and chief medical officer at Sobi, which is co-developing efanesoctocog alfa with Sanofi.

“The Breakthrough Therapy designation highlights efanesoctocog alfa’s potential to transform treatment for people with hemophilia A by providing higher protection for longer duration,” said John Reed, MD, PhD, global head of research and development at Sanofi.

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In hemophilia A, the body is unable to make a clotting protein called factor VIII (FVIII), resulting in uncontrolled bleeding. Replacement therapy, as the name implies, involves administering a version of the missing protein to restore blood clotting and prevent bleeds.

Efanesoctocog alfa, previously known as BIVV001, contains a version of the FVIII protein that has been modified to last longer in the body, thereby allowing for once-weekly dosing — markedly less frequently than other hemophilia A replacement therapies.

The FDA’s decision to award breakthrough therapy designation was based on top-line data from the open-label Phase 3 XTEND-1 clinical trial (NCT04161495). The trial enrolled 159 people with severe hemophilia A, ages 12 and older, who previously had been on either prophylactic (preventive) or on-demand FVIII replacement therapies. In the trial, participants switched to taking efanesoctocog alfa.

Results from XTEND-1 showed that efanesoctocog alfa led to clinically meaningful reduction in bleed rates. Additionally, bleed rates over one year were lower while patients were on efanesoctocog alfa than they had been on previous replacement therapies. The therapy also was generally well-tolerated; the most common adverse side effects were headache, joint pain, falling, and back pain.

Supported by data from XTEND-1, Sanofi and Sobi are planning to submit an application seeking the approval of efanesoctocog alfa in the U.S. later this year. The companies plan to seek approval in the European Union in 2023, after results come in from the Phase 3 XTEND-Kids study (NCT04759131), which is testing efanesoctocog alfa in boys with severe hemophilia A.

The FDA previously have efanesoctocog alga fast-track and orphan drug designations. The experimental therapy also has been designated an orphan drug in Europe.