Regenxbio Inc’s shares tumbled 24.3% in pre-market trading on Monday after the biotech company reported asymptomatic spine MRI findings in participants of its CAMPSIITE gene therapy study and said it would not resubmit a key Biologics License Application in the near term.
The stock, which had been trading at $8.12, fell to as low as $8.06 during the session. The decline extended a broader downward trend, with the company’s shares down roughly 50% from a 52-week high of $16.19 reached in August 2025. Regenxbio’s 52-week low stands at $5.46.
The MRI findings were identified in five participants who had received treatment between three and six years ago, according to the company. The U.S. Food and Drug Administration had previously placed a clinical hold on Regenxbio’s RGX-121 gene therapy in January 2026 following a separate case involving a central nervous system tumor in a participant treated with the related RGX-111 therapy. The FDA issued a Complete Response Letter for RGX-121 in February 2026.
Regenxbio said the MRI findings did not correlate with clinical symptoms and were not considered serious adverse events. However, the disclosure prompted Barclays to downgrade the stock from overweight to hold on August 7, 2026, and HC Wainwright to trim its price target from $26 to $23 on August 10, 2026. The company resumed trading at 7:25 a.m. ET on August 24, 2026.
Analysts noted the move was idiosyncratic to Regenxbio’s pipeline risks, with gene therapy peers not facing comparable regulatory actions. The broader market showed modest declines, with the Dow Jones Industrial Average down 0.1% and the Nasdaq Composite slipping 0.5%.
