In Vivo Gene Editing for Rare Diseases Begins with Umbrella Clinical Trial

It’s been less than six months since the news of Baby KJ broke, a watershed moment for precision medicine with the first successful demonstration of a personalized in vivo gene-editing therapeutic . But for Becca Ahrens-Nicklas, MD, PhD, the physician who cared for KJ, and Kiran Musunuru, MD, PhD, the cardiologist and gene-editing researcher who designed the therapy, that single success was the requisite first domino to fall in the journey to developing approved gene-editing therapies for the countless other individuals with monogenic inherited diseases.

What unfolded at the Children’s Hospital of Philadelphia (CHOP) in 2025 was at once a singular act of medical innovation and the beginning of a deliberate, systems-level effort to make such feats reproducible. The treatment of KJ wa