RARE Daily

FDA Grants Stealth BioTherapeutics Rare Pediatric Disease Designation for Barth Syndrome Therapy

March 3, 2020

The U.S. Food and Drug Administration has granted Stealth BioTherapeutics Rare Pediatric Disease designation for its experimental therapy elamipretide for the treatment of Barth syndrome, an ultra-rare genetic condition.

Photo: Reenie McCarthy, CEO of Stealth

Barth syndrome is characterized by cardiac abnormalities often leading to heart failure and reduced life expectancy, recurrent infections, muscle weakness, and delayed growth. It occurs almost exclusively in males and is estimated to affect one in 200,000 to 400,000 individuals worldwide. There are currently no FDA- or EMA-approved therapies for patients with Barth syndrome.

Elamipretide targets the inner mitochondrial membrane where it associates with cardiolipin—the signature phospholipid of the inner mitochondrial membrane, which plays a role in many mitochondrial processes, including respiration and energy conversion. In preclinical and clinical studies, elamipretide was shown to increase mitochondrial respiration, improve the electron transport chain function and ATP production, and reduce formation of pathogenic reactive oxygen species levels.

During an open-label extension of a study to evaluate the safety, tolerability, and efficacy of 12 weeks of treatment with elamipretide in individuals with genetically confirmed Barth syndrome, Stealth observed significant improvement in cardiac stroke volume.

“This designation for elamipretide underscores our alignment with the FDA around the significant and urgent unmet medical need for Barth patients,” said Reenie McCarthy, CEO of Stealth.  “We hope to improve the healthspan of Barth patients, for whom cardiomyopathy, exercise intolerance and debilitating fatigue limit life expectancy and impair quality of life. We are also expanding our development efforts to consider trials in patients suffering from overlapping metabolic cardiomyopathies in diseases such as Duchenne and Becker muscular dystrophies, and Friedreich’s ataxia.”

The FDA grants Rare Pediatric Disease designation for serious or life-threatening diseases with manifestations in individuals aged from birth to 18 years, including access to the FDA’s expedited review and approval process. The designation makes elamipretide eligible for a Rare Pediatric Disease Priority Review voucher upon approval of the therapy by the FDA.

The vouchers can be used to reduce the time of an FDA new drug approval review to six months from ten months. The vouchers are potentially lucrative because they are transferable. Most recently, Sarepta sold its Rare Pediatric Disease voucher to Vifor Pharma $111 million in February 2020.

Stealth has already received Fast Track and Orphan Drug designations from the FDA for the development of elamipretide as a treatment for Barth.

In October 2019, Alexion Pharmaceuticals paid Stealth $30 million for an option to co-develop and commercialize elamipretide for mitochondrial diseases. In late December, Stealth reported that elamipretide failed to meet the primary endpoints of a late-stage study for the treatment of primary mitochondrial myopathy, another rare mitochondrial dysfunction disorder.

Editor’s note: This story was updated to correct the most recent sales of a rare pediatric disease voucher.

Author: Rare Daily Staff

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