Regenxbio Won't Resubmit US FDA Biologics License Application for Hunter Syndrome Therapy; Shares Down Pre-Bell

07:35 AM EDT, 08/24/2026 (MT Newswires) -- Regenxbio (RGNX) does not plan to resubmit the biologics license application for its investigational gene therapy RGX-121 for Hunter syndrome in the near term following a US Food and Drug Administration clinical hold, the company said Monday. The FDA's decision follows the discovery of asymptomatic spine MRI findings in five participants who received RGX-121 three to six years ago, the company said. Investigators deemed the findings non-serious, and radiologists believe they are likely benign, though their nature and cause have not been confirmed, Regenxbio said. Regenxbio said all five patients remain clinically well, with stable to improved neurocognitive and neurobehavioral assessments. Shares of the company were down more than 26% in Monday's premarket activity.