REGENXBIO shares are down significantly due to an FDA clinical hold on their key gene therapy candidate, RGX-121. This hold, triggered by unexpected MRI findings, raises concerns about the drug's safety profile and delays its development timeline, impacting investor confidence.
The FDA clinical hold on RGX-121 is a significant negative catalyst for REGENXBIO (RGNX) as it directly impacts their lead gene therapy candidate for MPS II. The discovery of asymptomatic spine MRI findings, even if not immediately severe, raises safety concerns that the FDA will scrutinize, leading to delays and increased development costs. This event could also cast a shadow over the broader gene therapy sector, as any safety issues in one program can lead to heightened regulatory scrutiny for others. Investors will likely de-risk their positions in RGNX, and potentially other gene therapy companies, until more clarity emerges regarding the nature and implications of these findings.