Biotech & Genomic Medicine▼impact 4
FDA Clinical Hold on RGX-121 Sends REGENXBIO Stock Down 25%
REGENXBIO shares plunged 24.9% on Monday after the FDA placed a clinical hold on its investigational gene therapy RGX-121 for Mucopolysaccharidosis Type II, also known as Hunter syndrome. The hold followed asymptomatic spine MRI findings in five participants in the phase I/II/III CAMPSIITE study, who had received RGX-121 approximately three to six years earlier. The company no longer expects to resubmit the biologics license application for RGX-121 in the near term, after previously planning a third-quarter 2026 resubmission. REGENXBIO and NS Pharma are evaluating additional patient imaging and longer-term follow-up data and will incorporate FDA feedback into next steps. Attention is likely to shift to other pipeline programs, including RGX-202 for Duchenne muscular dystrophy, for which a BLA is planned in the third quarter of 2026.