Regenxbio's Hunter syndrome gene therapy hits second regulatory snag

Regenxbio's Hunter syndrome gene therapy program received its second clinical hold of the year, prompting the company to withdraw its expectations for an FDA submission in the near term. The hold adds uncertainty to the therapy's development timeline.

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Gene therapy for rare genetic disorders like Hunter syndrome has long been a promising but challenging frontier. Clinical holds—regulatory pauses imposed during development—can arise from safety signals, manufacturing concerns, or incomplete data, and a second hold within a single year often signals deeper, unresolved issues. For Regenxbio, this setback forces a reassessment of its program's trajectory, pushing any potential FDA submission further into the future. Hunter syndrome is a progressive, life-limiting lysosomal storage disease, and patients and families closely track such milestones. Each delay extends the wait for a possible one-time treatment, while