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 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 2 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.
Great Ormond Street argues that by taking its results and Paris' together present indications are that gene therapy is still safer and less intrusive than the conventional treatment for those children without a good bone marrow donor match. The hospital has pledged to continue to try to minimize risks to patients through protocols and better design. The current gene therapy treatment for X-SCID is being replaced by a new vector that has been designed to reduce the risk. There are no plans to use the hospital’s old vector to treat future children.
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.
Illustration: David Phillip Vetter, the original "Bubble Boy," left a deep mark on a world he visited only briefly. David's life contributed to scientific understandings and treatments of severe combined immunodeficiency (SCID), the disease that kept him in the bubble. Scientists and doctors have capitalized on David's experience to develop treatments for other children without robust immune systems. –Picture, Baylor College of Medicine Archives. –Text, PBS, “The Boy in the Bubble.”
Yahoo! News (12/18/07)
Scientific American (12/18/07)
Fox News (12/18/07)
BBC (1) (12/18/07)
BBC (2) (12/18/07)
PBS “The Boy in the Bubble” (04/10/06)