Can FDA tolerate cancer risk for rare pediatric disease gene therapies?

As AAV gene therapies reach more patients, the field is confronting a new reality: rare, long-latency cancers are no longer just a theoretical concern. The development is forcing fresh scrutiny of how cancer risk should be measured, how regulators should respond, and how much uncertainty can be tolerated in trials for devastating pediatric rare diseases.

At the end of January, FDA placed a clinical hold on a pair of clinical trials testing Regenxbio Inc. (NASDAQ:RGNX) gene therapies RGX-111 for mucopolysaccharidosis (MPS) I and RGX-121 for MPS II, respectively. The hold comes after an MPS type I patient developed a neoplasm four years after receiving RGX-111...