Stealth Biotherapeutics Announces FDA Acceptance Of New Drug Application For Elamipretide For The Treatment Of Barth Syndrome

• Barth Syndrome is an Ultra-rare, Progressive, Life-Shortening, Cardioskeletal Disease that Affects Approximately 150 Individuals in the United States
• If Approved, Elamipretide Would Become the First Approved Therapy for Barth Syndrome

Needham, MA /PRNewswire/ - Stealth BioTherapeutics, a clinical-stage biotechnology company focused on the discovery, development and commercialization of novel therapies for diseases involving mitochondrial dysfunction, today announced that the U.S. Food and Drug Administration ("FDA") has accepted for filing its New Drug Application ("NDA") for elamipretide for the treatment of Barth syndrome. The NDA is supported by the positive data from the SPIBA-001 Phase 3 Natural History Control Study and additional supporting efficacy and safety data from the TAZPOWER Part 2 baseline-controlled trial. Elamipretide received Fast Track Designation in 2017, Orphan Drug Designation in 2018 and Rare Pediatric Disease Designation in 2020.

"We are grateful that the FDA has listened to the voices of patients, families, and advocates who have been calling for a fair, appropriate, and complete review of elamipretide, which is the only medicine in late-stage clinical development for Barth syndrome," said Kate McCurdy, Chair of the Barth Syndrome Foundation. "This devastating disease has claimed the lives of too many of our children, loved ones, and friends. For those who survive past childhood, quality of life is severely diminished due to extreme muscle weakness, fatigue, and the constant threat of a life-threatening cardiac event. Our community desperately needs a treatment to enable us to live healthy and thriving lives."

The FDA indicated that it is currently planning to hold an advisory committee meeting to discuss the application. The application was assigned a standard review designation, which the Company has asked FDA to reconsider.

"We are pleased that the FDA has not only filed our NDA for Barth syndrome but has also committed to a transparent review process with its decision to convene an advisory committee," said Reenie McCarthy, Chief Executive Officer. "We welcome the input of committee experts to advise FDA on the seriousness of this devastating disease and the urgency of the unmet need, including in light of FDA's puzzling review designation. We look forward to working with the FDA through the review process."

If approved, this would be the first marketing authorization for elamipretide, a first-in-class mitochondrial targeted therapeutic. Elamipretide is also in development for primary mitochondrial myopathy, with pivotal data from the fully-enrolled Phase 3 NuPOWER trial expected in late 2024.

About Barth Syndrome
Barth syndrome is an ultra-rare genetic condition characterized by cardiac abnormalities leading to exercise intolerance, muscle weakness, debilitating fatigue, heart failure, recurrent infections, and delayed growth. The disease is associated with reduced life expectancy, with 85% of early deaths occurring by age 5. Barth syndrome occurs almost exclusively in males and is estimated to affect one in 1,000,000 males worldwide or around 150 individuals in the United States. There are currently no FDA- or EMA-approved therapies for patients with Barth syndrome. Elamipretide has Orphan Drug, Fast Track and Rare Pediatric Designation from the FDA and Orphan Drug Designation from the EMA for the treatment of Barth syndrome.

About Stealth BioTherapeutics
Stealth BioTherapeutics is a clinical-stage biotechnology company focused on the discovery, development, and commercialization of novel therapies for diseases involving mitochondrial dysfunction. Mitochondria, found in nearly every cell in the body, are the body's main source of energy production and are critical for normal organ function. Dysfunctional mitochondria characterize a number of rare genetic diseases and are involved in many common age-related diseases, typically involving organ systems with high energy demands such as the heart, the eye, and the brain. The Company believes its lead product candidate, elamipretide, has the potential to treat rare diseases including Barth syndrome and primary mitochondrial myopathy and common age-related diseases including dry age-related macular degeneration. The Company is also evaluating a topical ophthalmic formulation of its second-generation clinical-stage candidate, SBT-272, for dry age-related macular degeneration. The Company has a deep pipeline of novel compounds under evaluation for rare neurological and cardiac disease indications following promising preclinical data.