Neuroepithelial Tumor with AAV Integration after Intracisternal Magna Vector Delivery.

Recombinant adeno-associated virus (AAV) vectors are predominantly nonintegrating, but rare genomic integration events have been associated with oncogenesis in neonatal murine models. Here we report a case of a neuroepithelial tumor that developed in a 5-year-old boy with severe mucopolysaccharidosis type I (MPSI, Hurler subtype) 4 years after intracisternal magna administration of AAV serotype 9 gene therapy. The patient underwent successful resection of the primary tumor. Postoperatively, he has continued to have advanced cognitive function for his age, a finding that indicates mitigation of MPSI. Molecular analysis of the tumor showed clonal integration of rearranged AAV vector elements into the gene PLAG1 and expression of a chimeric AAV-PLAG1 transcript.