FDA Grants Stealth Fast Track Designation for Elamipretide in Barth Syndrome

The U.S. Food and Drug Administration (FDA) has granted Stealth BioTherapeutics fast track designation for elamipretide as a treatment for people with Barth syndrome, a rare mitochondrial disease.

The designation may shorten the time it takes for the treatment to reach patients. Elamipretide is currently being studied in the Phase 2/3 TAZPOWER clinical trial (NCT03098797), which is still recruiting participants.

“Fast Track designation is an important milestone which will facilitate Stealth’s efforts to develop an effective treatment for the Barth syndrome patient community, for whom there are currently no FDA-approved therapies,” Reenie McCarthy, Stealth’s CEO, said in a press release.

Elamipretide also has been granted fast track designation for its development for patients with primary mitochondrial myopathy (PMM), for which it recently also received orphan drug status.

The designation speeds up regulatory processes by allowing Stealth to attend more frequent meetings with the FDA during the therapy’s development. It also makes it possible to use so-called rolling submissions — submitting parts of a new drug application for review, rather than waiting for the entire application to be complete.

Barth syndrome, one of many rare mitochondrial diseases, almost always affects boys. It causes muscle weakness, heart problems that often lead to heart failure, and delayed growth. Low numbers of white blood cells cause recurrent infections and people with Barth syndrome risk early death.

The condition is caused by mutations in the TAZ gene, important for normal energy-making processes of the mitochondria. Elamipretide treatment aims to restore these processes.

The TAZPOWER trial started enrolling Barth patients in July 2017. The study is performed at the McKusick-Nathans Institute of Genetic Medicine of the Johns Hopkins University School of Medicine and enrolls boys with genetically confirmed Barth syndrome, aged 12 or older.

The trial is a so-called cross-over study, in which patients receive both elamipretide and placebo. One group starts with subcutaneous injections of elamipretide for 12 weeks and then switches to placebo for an equal stretch of time. The other group does the same in the reverse order.

This type of study makes interpretation of study results more robust.

“We are committed to developing treatments for patients suffering from rare mitochondrial diseases such as Barth syndrome, and look forward to working closely with the FDA in addressing this critical unmet need,” said McCarthy.