Shares of Regenxbio Inc. (NASDAQ: RGNX) tumbled 24.3% in pre-market trading to $8.12 after the U.S. Food and Drug Administration (FDA) placed a clinical hold on the gene therapy RGX-121.
The suspension follows the identification of asymptomatic findings in spinal magnetic resonance images (MRIs) from five participants in the CAMPSIITE study. These participants received the treatment between three and six years ago, and the findings were described as small nodules or cystic masses. Regenxbio stated it does not expect to resubmit the Biologics License Application (BLA) for RGX-121 in the near term, indefinitely delaying a key regulatory milestone.
The FDA’s action marks the second clinical hold imposed on Regenxbio’s gene therapy pipeline in 2026. A prior hold was triggered in January following a central nervous system tumor case in a participant treated with a related therapy, RGX-111. The company also received a Complete Response Letter for RGX-121 in February 2026, further complicating its regulatory pathway.
Analysts have responded with downgrades. Barclays reduced its rating from overweight to hold on August 7, while HC Wainwright lowered its price target from $26 to $23 on August 10. The stock’s 52-week range stands at a high of $16.19 and a low of $5.46, underscoring the volatility in its valuation.
The broader market showed limited reaction, with the S&P 500 down marginally, the Dow Jones falling 0.1%, and the Nasdaq declining 0.5%. No comparable regulatory actions were reported for other gene therapy companies on the same day, making the selloff idiosyncratic to Regenxbio.
