The FDA has placed clinical holds on two Regenxbio gene therapy studies after a patient in one program developed cancer, prompting the agency to pause enrollment and dosing while it reviews safety data. The company disclosed the regulatory action in recent filings and is cooperating with the agency’s inquiries. Clinical holds tied to potential malignancies in gene therapy trials are high‑impact events that can stall approval timelines and trigger program re‑evaluations. Sponsors typically respond with additional nonclinical analyses and safety monitoring plans; investors and partners will watch for the firm’s remediation steps and any impact on related vectored gene programs.