The FDA extended its review of Capricor Therapeutics’ Duchenne muscular dystrophy cell therapy candidate deramiocel, deferring a decision after a negative advisory committee vote. In parallel, the updated review scope is described as “refined,” with the agency seeking additional data before moving toward a PDUFA decision window. Separately, the FDA has again paused Regenxbio’s Hunter syndrome (MPS II) gene therapy RGX-121 after investigators detected masses on the spines of five patients. Regenxbio said none of the patients had symptoms related to the findings, but the hold adds another safety checkpoint to the refiling timeline. Taken together, the actions underscore how post-committee data scrutiny and imaging findings can quickly reshape development and commercialization cadence for advanced biologics. For gene therapy sponsors, spine MRI abnormalities have become a focal risk signal requiring careful monitoring and protocol adjustments. Biotech teams watching regulatory strategy are likely to treat both updates as near-term signals on how quickly FDA will accept revised indications (Capricor) or restart paused registrational pathways (Regenxbio) once new information is submitted and reviewed.