Regulatory NewsBREAK: The FDA Releases Draft Framework to Accelerate Individualized Therapies for UltraRare Diseases

On February 23, 2026, the U.S. Food and Drug Administration (FDA) released draft guidance outlining a new regulatory framework to support approval of individualized therapies for ultra-rare diseases when randomized controlled trials are infeasible because of extremely small patient populations.  

Issued jointly by the Center for Biologics Evaluation and Research and the Center for Drug Evaluation and Research, the draft guidance introduces a “Plausible Mechanism Framework” under which sponsors may rely on well-characterized natural history data, confirmation of target engagement, and evidence that a therapy addresses a clearly defined genetic or molecular cause of disease to support effectiveness and safety.

The FDA notes that small-sample clinical investigations may be acceptable under this framework, provided the results are sufficiently robust to exclude chance findings. For traditional approval, sponsors would still be expected to demonstrate improvement in clinical outcomes, disease course, or validated biomarkers predictive of clinical benefit.

The guidance also signals flexibility for genome-editing therapies, allowing multiple product variants targeting different mutations within a single gene to be evaluated under a single application using master protocols. Additional variants could be added post-approval based on a supported mechanism of action.

If finalized, the framework could affect evidence expectations, regulatory precedent, and downstream coverage considerations for individualized therapies targeting ultra-rare conditions. The draft guidance is open for public comment within 60 days of publication.

More on This Topic:

• Draft Guidance
• News Release

For questions, please reach out to Vicky Jucelin.