Dive Brief:

• Stealth Biotherapeutics on Tuesday said that a Food and Drug Administration deadline to approve its experimental rare disease drug has passed without a decision, and that the agency hasn’t yet set a new date by which the therapy might be cleared for use in the U.S.
• The company previously reported in January that the FDA had delayed a verdict on its Barth syndrome drug, elamipretide, so it could review information Stealth submitted following an October meeting of agency advisers. But the FDA didn’t cite any safety issues or require Stealth to conduct more tests, and set an April 29 deadline to complete its review.
• The delay comes amid steep staff cuts at the FDA that have heightened concern over its ability to meet drug review deadlines. Many have been met so far, though at least two companies, Novavax and Vanda Pharmaceuticals, have reported unexpected delays in agency decisionmaking.

Dive Insight:

The ongoing review of elamipretide is Stealth’s second chance at a drug approval. The company first brought elamipretide to the FDA in 2021, but the regulator declined to review it, arguing that Stealth hadn’t clearly proven its effectiveness.

Stealth has since stayed the course in pursuing the drug’s approval in Barth syndrome, an ultra-rare condition estimated to affect about 150 people in the U.S. The disease causes muscle weakness, heart failure and, often, an early death.

The FDA was still skeptical of the company’s study results and asked a committee of experts to review them. A majority of panelists concluded the drug was effective in testing, paving the way for a decision this year. Stealth had been granted a priority review as well, a tool the agency uses to fast track drug reviews.

That decision has now been delayed twice, and the latest holdup comes a month after the announcement of thousands of layoffs at the FDA. The agency has said drug reviewers won’t be affected and, since then, has met multiple approval deadlines, including on Tuesday a cell therapy from Abeona Therapeutics. Stealth CEO Reenie McCarthy, in the company’s statement, also said that the agency has been working with the biotech to “progress its review” and recently began labeling discussions.

However, the agency’s deadline has passed without a verdict or a new decision date. The company hopes “to gain more information” about the new date “in the coming days,” McCarthy said.

Emily Mulligan, director of the non-profit Barth Syndrome Foundation, added that her group is urging the FDA to “stay focused on completing this review” and providing a “clear new decision date.”

Several senior FDA leaders have left the agency in recent months, including Peter Marks, who oversaw the Center for Biologics Evaluation and Research, and Peter Stein, head of the FDA’s Office of New Drugs.

Editor’s note: This story has been updated to correct the indication for which elamipretide received a refuse-to-file letter in 2021.