An FDA advisory committee may have ruled in elamipretide’s favor back in October, but it looks like Stealth BioTherapeutics will have to remain patient a while longer before it finally finds out whether the Barth syndrome treatment will get the green light.
Three months ago, the FDA’s Cardiovascular and Renal Drugs Advisory Committee voted 10-6 in support of elamipretide becoming the first approved treatment for Barth syndrome, an X-linked genetic disorder that weakens the heart and other muscles. A PDUFA date was set for Jan. 29 for the new drug application (NDA), but the biotech announced today that the FDA has pushed this back to April 29.
The agency requested the three-month delay to review additional data supplied by Stealth, the biotech explained. The FDA ruled that these data counted as a major amendment to the approval request, triggering the standard three-month extension to the decision timeline.
The FDA hasn't flagged any safety issues nor requested any new studies, Stealth stressed in its release.
“We continue to work closely with the agency as it completes its review of the elamipretide NDA and are actively preparing to support broad access to this therapy for individuals living with Barth syndrome as quickly as possible following potential approval,” Stealth CEO Reenie McCarthy said in the release.
The delay is only the latest obstacle in elamipretide’s journey to hoped-for approval. The FDA turned down Stealth’s original application in Barth syndrome back in 2021 on the grounds that the request didn’t contain a single adequate and well-controlled trial that could establish efficacy.
While the FDA recommended the company run a new late-stage trial, Stealth later informed the agency of its intent to resubmit the NDA without conducting a new trial. The regulator said it could not prevent an applicant from resubmitting and that Stealth should fully address its prior concerns in the resubmission.
In briefing documents ahead of the cardiovascular committee’s October meeting, the FDA argued Stealth’s data package was still likely not enough to warrant an approval, even via an accelerated pathway. The agency considered data from a phase 2 study, an open-label crossover follow-up, and a phase 3 trial evaluating elamipretide’s effect in a distance-walked test, among other things.
During the committee meeting, McCarthy said that “in retrospect … I think we severely underestimated the hurdles that we would face, but we really persevered because we were inspired by the potential that we believe we've delivered upon to improve the lives of patients living with this serious, rare disease.”