A three-year-old "bubble boy" undergoing pioneering gene therapy in London has developed leukemia, marking another setback for the experimental treatment. Doctors at Great Ormond Street Hospital said on Tuesday the boy had been successfully treated for SCID-X1, or x-linked severe combined immunodeficiency, often known as "baby in the bubble syndrome", but had developed leukemia two years later. The news is a blow to the treatment program at the London hospital, which has a worldwide reputation from treating sick children.
Although gene therapy has been linked to leukemia before, this is the first such case within the London hospital's program. Doctors said they were now seeking improved formulations of the genetic medicine for new trials next year. Five years ago, similar cases of leukemia were seen in two French boys given gene therapy. Researchers believe in that case the experimental treatment triggered a gene that caused their bone marrow to overproduce immune system cells called T-cells.
Leonard Seymour, professor of gene therapies at the University of Oxford, said the latest case showed the need to balance the risks for patients, given that gene therapy is often the only hope. Childhood leukemia is generally treatable, with cure rates of 90 percent or more. In contrast, children with SCID who cannot get a bone marrow transplant almost always die within a year.Read full story » see also X-SCID statement