RARE Daily

Sanofi and Sobi Report Positive Results for Once Weekly Hemophilia A Therapy

March 9, 2022

Sanofi and Swedish Orphan Biovitrum reported positive topline results from the pivotal XTEND-1 phase 3 study evaluating the safety, efficacy and pharmacokinetics of its once-weekly factor VIII replacement therapy efanesoctocog alfa in previously treated patients 12 years of age and older with severe hemophilia A.

Photo: Dietmar Berger, global head of development and chief medical officer of Sanofi

The study met the primary endpoint, showing a clinically meaningful prevention of bleeds in people with severe hemophilia A receiving weekly prophylaxis with efanesoctocog alfa over a period of 52 weeks. The median annualized bleeding rate (ABR) was 0 with a mean ABR of 0.71.

The key secondary endpoint was also met, demonstrating once-weekly efanesoctocog alfa was superior to prior prophylactic factor VIII replacement therapy, showing a statistically significant reduction in ABR based on intra-patient comparison. Efanesoctocog alfa was well-tolerated, and inhibitor development to factor VIII was not detected. The most common treatment-emergent adverse events (>5% of participants overall) were headache, arthralgia, fall, and back pain.

Hemophilia A is a rare, genetic disorder in which the ability of a person’s blood to clot is impaired due to a lack of factor VIII. Hemophilia A occurs in about one in 5,000 male births annually, and more rarely in females. People with hemophilia can experience bleeding episodes that can cause pain, irreversible joint damage, and life-threatening hemorrhages.

Efanesoctocog alfa is a novel and investigational recombinant factor VIII therapy that is designed to extend protection from bleeds with once-weekly prophylactic dosing for people with hemophilia A. It builds on the innovative Fc fusion technology by adding a region of von Willebrand factor and XTEN polypeptides to extend its time in circulation. It is the first investigational factor VIII therapy that has been shown to break through the von Willebrand factor ceiling, which imposes a half-life limitation on current factor VIII therapies. Efanesoctocog alfa is currently under clinical investigation and its safety and efficacy have not been evaluated by any regulatory authority.

“While advances have been made in the treatment of hemophilia, unmet medical needs still exist. These positive topline data, showing a very low annualized bleeding rate, enhance efanesoctocog alfa’s potential to transform hemophilia A therapy,” said Dietmar Berger, global head of development and chief medical officer of Sanofi. “We believe efanesoctocog alfa provides higher protection for longer duration with reduced treatment burden of once-weekly dosing, and we look forward to working with regulators to bring this therapy to patients as soon as possible.”

The data will be the basis for submission to regulatory authorities around the globe beginning this year. Submission in the European Union will follow availability of data from the ongoing XTEND-Kids pediatric study, expected in 2023.

Efanesoctocog alfa was granted Orphan Drug designation by the U.S. Food and Drug Administration in August 2017 and the European Commission in June 2019. The FDA granted Fast Track designation in February 2021.

Author: Rare Daily Staff

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