Researchers have launched a new gene-therapy trial for children with a rare disease known as "bubble boy syndrome," reflecting fresh hopes that the strategy of delivering working genes can be used to treat many intractable ailments.
In the new study, sponsored in the U.S. by investigators at Children's Hospital Boston and expected to open at five sites around the world, scientists plan to enroll 20 boys with SCID-X1, which stands for severe combined immunodeficiency, X-linked — a genetic condition that affects boys and leaves them unable to fight germs. Without treatment, which is currently possible only by bone-marrow transplantation, most children die before age one.
The study comes seven years after two similar trials in Europe — one in Paris and one in London, involving a total of 20 children — were temporarily halted when two participants were diagnosed with leukemia. Three others eventually developed the blood cancer, and one died. Those who survived were cured of SCID-X1, but the episode prompted the U.S. Food and Drug Administration to put a hold on certain gene-therapy studies.
While gene-therapy studies in other diseases have gone forward, the new trial is the first involving SCID-X1 to take place in the U.S. since the hold. Researchers believe they have stripped out the feature of the treatment that caused leukemia.
"If the trial is successful, we think what we are doing can apply to other rare diseases as well," said David Williams, chief of hematology/oncology at Children's Hospital Boston and lead investigator for the U.S. sites.
In gene therapy, scientists try to correct a problem caused by a defective or non-functioning gene. A normal gene is delivered via what scientists call a vector, typically a virus genetically altered to contain human DNA. The idea is that this normal gene will begin producing a protein that has been missing or not working and cure the disease.