An Ultra-Rare Disease Drug Developer Tries to Navigate Regulatory Uncertainty

When Stealth Biotherapeutics sought approval for its experimental therapy to treat the ultra-rare and life-threatening condition Barth syndrome, the U.S. Food and Drug Administration said it wouldn’t review its application because the clinical studies the company performed involved too few patients to make a determination about the efficacy of the drug. The notice was part of a history of interactions between Stealth and the FDA that that the company said was characterized by inconsistent guidance as it moved from division to division within the agency. We spoke to Reenie McCarthy, CEO of Stealth, about the challenges the company has faced in seeking FDA approval for its Barth syndrome therapy, the lack of consistency it found within the agency, and why this could have a chilling effect on the development of ultra-rare disease therapies if left unaddressed.