Timothy Yu

Rule Changes

Pioneer of individualized antisense oligonucleotide therapies

For decades, the Food and Drug Administration (FDA) required the same basic proof for every drug: show it works in a controlled trial with enough patients to be statistically meaningful. That standard made sense for common diseases but created an impossible barrier for conditions affecting a handful of people worldwide. On February 23, 2026, the FDA issued draft guidance creating a fundamentally different standard—called the "plausible mechanism" framework—that would let developers of individualized gene-editing and ribonucleic acid (RNA) therapies win full approval by demonstrating their treatment targets the root genetic cause, successfully edits or engages the target, and improves outcomes compared to the disease's documented natural course.

Updated Feb 23