Stealth BioTherapeutics Initiates Observational Study of Patients With Mitochondrial Myopathy

Study results to inform design and appropriate patient population for interventional Phase 3 clinical trial

BOSTON – March 2, 2017 – Stealth BioTherapeutics Inc. (Stealth), a clinical-stage biopharmaceutical company developing therapeutics to treat mitochondrial dysfunction, today announced the initiation of RePOWER, a prospective, observational study and pre-trial registry of patients with mitochondrial myopathy (MM). This study will be conducted in North America, Europe and Australia.

“We expect to use this study to help us design an interventional Phase 3 trial and further our understanding of elamipretide’s potential in this patient population,” said Jim Carr, Stealth’s Chief Clinical Development Officer. “Since mitochondrial disease has a heterogeneous clinical presentation, the results of this study will help us better characterize the disease burden impacting patients who may participate in our upcoming Phase 3 trial, as well as add to the scientific understanding of the disease. We hope that our scientific collaboration with the investigators will add to the work of others, and further the knowledge needed to find effective treatments for this disease.”

“As our mission is to be the leader in mitochondrial medicine, we’re committed to help fill the significant treatment gaps in primary mitochondrial disease, as well as in more common diseases associated with aging in which mitochondrial dysfunction is a contributory or causal factor,” said Stealth’s Chief Executive Officer Reenie McCarthy. “Severe fatigue and muscle weakness, or MM, is among the most common clinical presentations of primary mitochondrial disease, making it difficult for patients to complete simple daily tasks. Our goal with our MM program, as with all our programs, is to design clinical trials as thoughtfully as possible taking into account the clinical burden of disease on the patient population. We believe this study will help guide us as we work to develop therapies for MM and other primary mitochondrial diseases.”

For additional information on RePOWER or elamipretide, please refer to Stealth’s website and


RePOWER is a prospective, observational study and pre-trial registry of patients with genetically confirmed or suspected MM. MM affects those with genetically confirmed mitochondrial disease who show signs or symptoms suggestive of myopathy (e.g., easy fatigability, exercise intolerance, muscle pain). The study will assess approximately 300 subjects, ages 16-65, at a single enrollment visit, where they will complete questionnaires about their current symptoms and quality of life, and perform functional assessments. Data from patient clinical records will also be collected.

The primary objectives of this study include assessments of the relationship of genetic test results to the clinical presentation and regional differences in the standard of care and management of patients with MM. Secondary objectives include identifying a potential patient population for an upcoming interventional Phase 3, randomized, double-blind, placebo-controlled clinical trial and comparing regional differences in genetic testing methodologies. 

About Stealth BioTherapeutics

We are a privately held clinical-stage biotechnology company focused on the development of therapeutics for diseases involving mitochondrial dysfunction. We believe there is a strong rationale for our lead product candidate, elamipretide, in indications in these diseases based on encouraging preclinical and early clinical data. We are investigating elamipretide in three primary mitochondrial diseases – mitochondrial myopathy (MM), Barth syndrome and Leber’s hereditary optic neuropathy (LHON) – as well as in heart failure, Fuchs’ corneal dystrophy and dry age-related macular degeneration. We received Fast Track designation for elamipretide for the treatment of primary mitochondrial myopathy from the FDA in December 2015. We are developing our second product candidate, SBT-20, for central nervous system disorders. Our mission is to be the leader in mitochondrial medicine. To learn more information about us and our pipeline, visit

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