NEJM Reports Two Tumor Cases After AAV Gene Therapy With Vector Integration at GLI1 and PLAG1

A research letter in the October 15, 2026 issue of the New England Journal of Medicine describes a 3-year-old boy with infantile Krabbe disease who, 26 months after treatment with FBX-101 in an AAVrh.10 capsid, developed a paraspinal mass at lumbar levels L2-L3, pathologically confirmed as a tumor associated with GLI1 gene alteration. The same journal reported the first case in May: a child with severe MPS I developed an intraventricular neuroepithelial tumor 4 years after RGX-111 treatment, with vector integration into PLAG1.