September 19, 2025 - FDA Grants Accelerated Approval to First Treatment for Barth Syndrome

Today, the U.S. Food and Drug Administration granted accelerated approval to Forzinity (elamipretide) injection as the first treatment for Barth syndrome, in patients weighing at least 30 kg. Barth syndrome is a rare, serious and life-threatening disease of the mitochondria (the energy-producing parts of cells).

"The FDA remains committed to facilitating the development of effective and safe therapies for rare diseases and will continue to work diligently to help ensure patients with rare diseases have access to innovative treatments," said George Tidmarsh, M.D., Ph.D., Director of the FDA's Center for Drug Evaluation and Research.

Barth syndrome primarily affects males, typically starts with severe heart failure in infancy, and causes premature death. Patients who survive into adolescence and adulthood often have fatigue, poor stamina, and exercise intolerance. The quality of life and daily functioning of patients with Barth syndrome are significantly affected throughout their lives.

Forzinity works by binding to the inner part of the mitochondria, improving mitochondrial structure and function. FDA granted Forzinity accelerated approval. This pathway can allow earlier approval of medications that treat serious conditions and fill an unmet medical need on the basis of a measure that is considered reasonably likely to predict patient benefit but does not directly assess the benefit to the patient. Forzinity's accelerated approval is based on improved strength of the muscle used to straighten the leg at the knee. FDA considers this improvement reasonably likely to predict patient benefit, such as an ability to stand more easily or walk farther. As a condition of accelerated approval, FDA is requiring the manufacturer of Forzinity to conduct a post-approval randomized, double-blind, placebo-controlled trial to confirm that the changes seen on knee muscle strength translate into patient benefit.

Forzinity is administered subcutaneously (under the skin) once daily. The most common side effects identified in clinical trials were mild-to-moderate injection site reactions. Serious reactions to Forzinity have also been reported.

This application was granted priority review, and Forzinity was granted a rare pediatric disease designation. The FDA granted the accelerated approval of Forzinity, as well as a rare pediatric disease priority review voucher, to Stealth Biotherapeutics Inc.

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