FDA says it wants individualized medicines. Can we get there?

Washington, DC—At a press conference held at the US Department of Health and Human Services headquarters on Feb. 23, two doctors from the University of Pennsylvania and Children’s Hospital of Philadelphia spoke about their hope for the future of treating rare diseases.

Kiran Musunuru and Rebecca Ahrens-Nicklas treated Baby KJ, better known as the first person to receive a tailor-made gene therapy, in February 2025. That personalized CRISPR treatment helped Baby KJ, born with a urea cycle disorder that prevents his liver from breaking down ammonia, to eat more protein and require less of an ammonia-lowering medication. The US Food and Drug Administration now hopes to enable this kind of thing at scale.

At the press event, HHS officials launched guidance for a new FDA approval pathway based on what the agency calls a “plausible mechanism.” The agency says this clears the way for treatments like KJ’s to be scaled up to help others with his disorder even if they have different disease-causing mutations.

“The types of individualized genetic therapies that we're trying to develop simply do not...