Timothy Yu

Rule Changes

Pioneer of individualized antisense oligonucleotide therapies

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 On February 23, 2026, the FDA issued draft guidance for a new standard—the 'plausible mechanism' framework.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