FDA again paused Regenxbio’s Hunter syndrome gene therapy trial after investigators found masses on the spines of five treated patients, as reported by the company and covered by STAT+. Regenxbio said the patients were asymptomatic, but the safety signal has triggered another clinical hold. The development builds on earlier scrutiny around AAV gene therapy-associated findings and adds uncertainty to the company’s path for a future BLA submission. For the field, the repeated holds emphasize the need for durable, clinically accepted monitoring frameworks for long-term gene therapy safety signals.