Children's Hospital of Philadelphia

Rule Changes

Site of the first personalized CRISPR therapy for Baby KJ

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 On February 23, 2026, the FDA issued draft guidance for a new standard—the 'plausible mechanism' framework.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

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 restored hearing in dozens of patients, moving genetic deafness from permanent disability to treatable condition. The effect is rapid—most patients recover hearing within weeks and retain it for at least two years.

Updated May 19