A gene therapy given to a 13-month-old boy has, years later, led to a tumor in his brain after the virus carrying the gene inserted part of it directly into his DNA, researchers reported today at a meeting and in a paper. The mass was safely removed, but his case appears to be the first time a gene therapy delivered directly into the body has been linked to cancer.
Researchers involved with the case and others stress that the rare case does not mean the adeno-associated virus (AAV) the boy received, which has been given to thousands of people as part of gene therapies, should not be used. “We have to be really cautious in extrapolating this” to other AAV trials, says Lindsey George, who co-led the trial and presented the work at the annual meeting of the American Society of Gene & Cell Therapy.
The boy was born with Hurler syndrome, also known as MPS I, a condition in which certain sugars build up in the brain and damage it. It stems from a mutation in the gene encoding an enzyme called IDUA, which cells need to break down the sugars.