Stealth BioTherapeutics Completes Enrollment of Study for the Treatment of Barth Syndrome

Top-line data expected by the end of 2018

BOSTON – March 6, 2018 – Stealth BioTherapeutics (Stealth), a clinical-stage biopharmaceutical company developing investigational therapeutics to treat mitochondrial dysfunction, today announced the completion of enrollment in the TAZPOWER clinical trial, a phase 2/3, randomized, double-blind, placebo-controlled crossover study to evaluate the effects of daily treatment with elamipretide in 12 patients with genetically confirmed Barth syndrome. Barth syndrome is a rare and debilitating genetic mitochondrial disease that is estimated to affect one in 200,000 to 400,000 individuals worldwide. There are no treatments approved by the U.S. Food and Drug Administration (FDA).

“We are grateful for the support we have received from the Barth community in recruiting an estimated 10 percent of the U.S. adult Barth population to participate in this trial,” said Stealth Chief Executive Officer Reenie McCarthy. “We are eager to understand the therapeutic potential of elamipretide to treat this ultra-rare disease, and remain on track to announce top-line results later this year.”

Stealth initiated the TAZPOWER study in July 2017. The primary endpoint of the study is change in distance walked during the six-minute walk test and secondary endpoints include additional functional assessments, patient-reported outcomes and safety. In November 2017, Stealth announced that the FDA granted Fast Track designation for elamipretide for the treatment of Barth syndrome.

For additional information on the TAZPOWER study or elamipretide, please refer to Stealth’s website.

About Barth Syndrome

Barth syndrome is a rare genetic condition characterized by muscle weakness, cardiac abnormalities often leading to heart failure, recurrent infections, delayed growth, and reduced life expectancy. Barth syndrome occurs almost exclusively in males and is estimated to affect one in 200,000 to 400,000 individuals worldwide at birth. There are currently no FDA-approved therapies for the disease.

About Stealth

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 – primary mitochondrial myopathy (PMM), Barth syndrome and LHON – as well as in dry age-related macular degeneration. We received Orphan Drug Designation of elamipretide for the treatment of PMM from the FDA in September 2017. We are developing our second product candidate, SBT-20, for neurodegenerative diseases. To learn more information about us and our pipeline, visit


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