Tracy Beth Høeg

Stories

FDA creates new approval pathway for gene therapies tailored to individual rare disease patients

Leading CDER's role in the new framework

For decades, the FDA required all drugs to prove effectiveness through controlled trials with sufficient sample sizes, a standard that made sense for common diseases but created an impossible barrier for ultra-rare conditions. On February 23, 2026, the FDA issued draft guidance for a new standard—the 'plausible mechanism' framework. Developers of gene-editing and ribonucleic acid (RNA) therapies could win full approval by showing that their treatment targets the root genetic cause, engages it, and improves outcomes compared to the disease's natural course.

Updated May 29

Notable Quotes

"The Plausible Mechanism draft guidance creates a novel framework through which cutting-edge treatments tailor-made for patients with ultra-rare diseases can be used as a basis for FDA approval. We anticipate it will inspire industry to place increased focus on individualized therapies, thereby driving innovation, improving safety, lowering costs, and offering more patients with ultra-rare diseases a unique shot at a life-saving treatment." — FDA press announcement, February 2026

from FDA creates new approval pathway for gene therapies tailored to individual rare disease patients · Updated May 29