Children's Hospital of Philadelphia

Rule Changes

Site of the first personalized CRISPR therapy for Baby KJ

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 On February 23, 2026, the FDA issued draft guidance creating a fundamentally different standard—called the "plausible mechanism" framework—that would let developers of individualized gene-editing and ribonucleic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

New Capabilities

First U.S. site to administer gene therapy for genetic hearing loss

Children born profoundly deaf can now hear their parents' voices. A single injection of gene therapy into the inner ear has restored hearing in dozens of patients with genetic deafness, moving some forms of lifelong hearing loss from permanent disability into the treatable category. The effect is rapid—most patients recover hearing within weeks—and sustained over at least two years of follow-up.

Updated Jan 9