Regenerxbio’s Hunter syndrome gene therapy programs hit another regulatory snag, with the FDA placing clinical holds tied to asymptomatic spine MRI findings. The company said it no longer expects to file for FDA approval of its RGX-121 (clemidsogene lanparvovec) in the near term after discovering spine MRI masses in five patients enrolled in its Campsiite study, prompting a stop to testing. The new hold follows a prior Hunter-related pause earlier this year. STAT+ previously reported Regenxbio’s trial pauses for safety reasons, and the latest decision adds urgency for stakeholders tracking AAV gene therapy risk signals—especially around latent imaging abnormalities.