Stealth BioTherapeutics Corp. provided key takeaways from a presentation by Reenie McCarthy, the Company's Chief Executive Officer, at the World Orphan Drug Congress USA, held May 23-25 in Washington, D.C. In the presentation, entitled "Opp opportunities and challenges in Ultra-Rare Drug Development," McCarthy referenced the Company's Barth syndrome development program as a case study to highlight the need for new incentives and differentiated ultra-rare regulatory pathways to reduce health inequities faced by patients with ultra-rare diseases. Barth syndrome is an ultra-rare disease that affects approximately 250 people worldwide.

Key points from the presentation included: More than 90% of rare diseases do not have a single FDA-approved treatment. New incentives for ultra-rare diseases may be needed: Wall Street views rare diseases that affect fewer than 10,000 individuals (for small molecules) or fewer 1,000 individuals (for gene therapies) as uninvestable. Small biotechnology companies remain more active in ultra-rare drug development than large pharmaceutical companies, increasing funding uncertainty and need for incentives particularly in challenging capital markets.

FDA regulations do not distinguish between rare and ultra-rare diseases in applying regulatory flexibility despite the significantly increased risk of Type 2 error - the risk of not approving an effective drug - in ultra-rare diseases. Perspectives on flexibility and review pathways can vary between centers, divisions, and even clinical reviewers. decisions on when and how to apply flexibility are often made ad hoc.

The accelerated approval pathway for ultra-rare diseases presents opportunities, challenges, and the potential for positive change.