FDA Delays Decision on Elamipretide for Barth Syndrome

The US Food and Drug Administration (FDA) delayed the target action date for the New Drug Application (NDA) for the investigational medicine, elamipretide, for the treatment of Barth syndrome.1

Announced on April 30, 2025, Stealth BioTherapeutics indicated that labelling discussions were initiated with the regulatory agency; however, a revised action date has yet to be communicated for the application for the ultra-rare, life-threatening disease.

"We appreciate the diligent efforts of the FDA to progress its review of our NDA, including its confirmation of post-marketing requirements and its recent initiation of labeling discussions," said Reenie McCarthy, Chief Executive Officer of Stealth BioTherapeutics.1 "We hope to gain more information on the revised action date in the coming days to inform our ability to continue supporting expanded and emergency access to elamipretide while advancing towards a potential FDA approval."

An ultra-rare, genetic mitochondrial disease, Barth syndrome, affecting fewer than 150 individuals in the US and 300 individuals worldwide, occurs primarily in males. The disease has been linked to exercise intolerance, muscle weakness, debilitating fatigue, heart failure, recurrent infections, and delayed growth. Associated with a reduced life expectancy, approximately 85% of early deaths occur by age five—there are no approved therapies for the treatment of Barth syndrome.2

The initial NDA was submitted by Stealth to the FDA on January 29, 2024, and filed for standard review in March, with a target action date of January 29, 2025. On May 6, the regulatory agency granted Priority Review designation to the application for elamipretide.

By October 2024, the FDA’s Cardiovascular and Renal Drugs Advisory Committee (CRDAC) met and determined that elamipretide is effective for the treatment of Barth Syndrome. However, on January 14, 2025, the FDA announced its request for new analyses in November and December 2024 necessitated a delay of the PDUFA date to April 29, 2025.1

The FDA has awarded Elamipretide with Orphan Drug, Fast Track, Priority Review, and Rare Pediatric designations for the treatment of Barth syndrome. Elamipretide has also received Orphan Drug designation from the European Medicines Agency (EMA).3

In the release, Stealth Biotherapeutics announced that 35 patients worldwide have received expanded or emergency access to elamipretide for the treatment of Barth syndrome, including critically ill infants and toddlers impacted by the disease.1

References

1. Stealth Biotherapeutics announces delay in FDA action date for Barth Syndrome Application. Stealth BioTherapeutics Inc. April 29, 2025. Accessed April 30, 2025. https://stealthbt.com/stealth-biotherapeutics-announces-delay-in-fda-action-date-for-barth-syndrome-application/.

2. Ferreira C, Pierre G, Thompson R, Vernon H. Barth Syndrome. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, eds. GeneReviews®. Seattle (WA): University of Washington, Seattle; October 9, 2014.

3. Rossi K. FDA grants orphan drug designation to Elamipretide for bath syndrome. HCP Live. February 4, 2021. Accessed April 30, 2025. https://www.hcplive.com/view/fda-grants-orphan-drug-designation-to-elamipretide-for-the-treatment-of-bath-syndrome.