On Tuesday, Stealth Biotherapeutics announced that it plans to meet with the FDA to discuss a potential NDA for its therapeutic, elamipretide, which is intended to treat Barth syndrome.
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On Tuesday, Stealth Biotherapeutics announced that it plans to meet with the U.S. Food and Drug Administration to discuss a potential New Drug Application (NDA) for its therapeutic, elamipretide, which is intended to treat Barth syndrome.
The development comes amid a rocky journey. In August 2021, Stealth submitted an NDA for elamipretide, a small mitochondrially-targeted tetrapeptide, for the treatment of Barth syndrome. The FDA had granted the therapy orphan drug designation, rare pediatric designation and fast track designation.
Barth syndrome is a rare, genetic disorder that causes an enlarged and weakened heart, weakness in muscles and small numbers of white blood cells due to mutations in the gene TAFAZZIN which creates the protein tafazzin. This protein is important to the function of mitochondria. Those with the condition produce tafazzin proteins with little or no function, causing dysfunction in mitochondrial cells. There are currently no FDA-approved treatments for the condition, lending to elamipretide’s multiple designations.
The NDA submission was based on data from a Phase III clinical trial in which the drug met its primary and secondary endpoints and produced clinically meaningful improvements in biomarkers of cardiac function, exercise tolerance and strength. The trial compared data from treated patients to natural history controls, a method that uses retrospective data collected from patients, usually from medical records, rather than collecting data from controls that participated in the clinical trial.
At the time of the submission, the FDA recommended additional controlled data be generated to support NDA review, but Stealth stated that neither the company nor the regulatory agency had identified a suitable trial design. Stealth forged ahead with the data submission, namely because conducting additional clinical trials in the population would prove difficult as less than 130 people in the U.S. are diagnosed with the condition.
The additional data needed would prove to be Stealth’s downfall in October 2021 when the company received a Refusal to File letter from the FDA. The agency stated that the NDA the company had submitted was not sufficiently complete to warrant a substantive review, citing again the lack of an adequate and well-controlled trial that provides efficacy evidence. At the time, Stealth stated that the FDA did not provide reasoning as to why its retrospective controls were not considered adequate.
Now, the FDA has granted Stealth a pre-NDA meeting to discuss new clinical data collected over 3.5 years from its open-label extension period of a Phase II study. The meeting is set to take place sometime in the third quarter.
“We welcome the opportunity to meet with FDA to discuss our promising new clinical data and a potential NDA submission,” Reenie McCarthy, CEO of Stealth said. “We look forward to working with the Agency toward our goal of securing the regulatory review and approval necessary to make elamipretide available to patients with Barth Syndsararome. We are eager to present our new clinical data at an upcoming scientific meeting.”
