FDA Grants Priority Review of Efanesoctocog Alfa for Hemophilia A

FDA decision on longer-lasting replacement therapy due February 2023

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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The U.S. Food and Drug Administration (FDA) has granted priority review for the approval of efanesoctocog alfa, with a decision on the potentially longer-lasting hemophilia A treatment due early next year.

The regulatory agency accepted an application from developers Sobi and Sanofi requesting approval of the experimental replacement therapy, designed for once-weekly dosing for hem A patients. A target action date for the FDA decision has been set for Feb. 28, 2023.

Priority review aims to shorten the time to possible approval for therapies that have the potential to substantially improve care for serious medical conditions.

The FDA had previously awarded efanesoctocog alfa breakthrough therapy, orphan drug, and fast track designations, all of which accelerate the development and review of new treatments.

“We look forward to working closely with the FDA during the review process as we aim to bring this novel therapy to the hemophilia A community,” Dietmar Berger, MD, PhD, Sanofi’s global head of development and chief medical officer, said in a press release.

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Once-weekly Efanesoctocog Alfa Prevents Bleeds in Severe Hem A

Efanesoctocog alfa in clinical trials

Hemophilia A is caused by mutations that impair the function of a clotting protein called factor VIII (FVIII). As a replacement therapy, efanesoctocog alfa contains a working version of this protein that has been modified to last longer in the body than those in currently approved regimens. The new treatment would thus allow for less frequent dosing compared with other approved replacement therapies for hemophilia A.

“Factor [replacement] therapy remains a cornerstone of hemophilia treatment, but innovation has been needed in this area to address challenges related to bleed protection and cumbersome treatment regimens,” said Steve Pipe, MD, a professor at the University of Michigan and director of the pediatric hemophilia and coagulation disorders program.

The application requesting the therapy’s approval was supported by data from the Phase 3 XTEND-1 trial (NCT04161495), which evaluated efanesoctocog alfa in 159 adults and adolescents with severe hemophilia A. The participants, all ages 12 and older, previously had been treated with other FVIII replacement therapies.

Results showed that treatment with efanesoctocog alfa significantly reduced yearly bleeding rates, by an average of 77%, compared with the prior replacement therapies. Efanesoctocog alfa boosted FVIII activity as intended, led to improvements in joint health, and reduced pain. The most common adverse events reported during trial were headache, joint pain, fall, and back pain.

“The results from the pivotal XTEND-1 Phase 3 study demonstrate efanesoctocog alfa’s ability to reduce annualized bleeding rates, which supports its potential as a therapy with best-in-disease efficacy,” Berger said.

Pipe said the therapy could give more options for preventive treatment for hemophilia A patients.

“If approved, efanesoctocog alfa can deliver close to normal factor activity levels for the majority of the week, potentially offering a new tier of protection. Such therapeutic benefits would represent important advances in unmet medical needs for people with hemophilia A and may transform the prophylactic treatment landscape,” Pipe added.

Sanofi and Sobi are planning to submit an application requesting the approval of efanesoctocog alfa in Europe next year. That application is expected once the results from the Phase 3 XTEND-Kids study (NCT04759131), which is testing the therapy in younger children with severe hemophilia A, become available. Regulatory authorities in the EU also had previously granted orphan drug designation to efanesoctocog alfa.