Needham, Massachusetts, USA

Stealth BioTherapeutics

US biotechnology company working on mitochondria-targeted medicines. Its elamipretide is a peptide that the US FDA approved in September 2025 under the brand FORZINITY, under accelerated approval, for Barth syndrome. The company's current website says it is now named Mighty Therapeutics. It is not a GLP-1 developer.

FDA accelerated approval

FDA's approval letter for NDA 215244, addressed to Stealth BioTherapeutics Inc. and signed on 2025-09-19, grants accelerated approval to Forzinity (elamipretide) injection to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg. The letter also grants the company a rare pediatric disease priority review voucher.[src]

Accelerated approval basis and confirmatory evidence

The FORZINITY label states the indication is approved under accelerated approval based on an improvement in knee extensor muscle strength, an intermediate clinical endpoint, and that continued approval may be contingent upon verification and description of clinical benefit in a confirmatory trial.[src]

Company name

The company's current website states it was formerly named Stealth BioTherapeutics and is now Mighty Therapeutics, with its address in Needham, Massachusetts.[src]