Researchers in Italy and Israel have announced that they have successfully used gene therapy to treat ten children who suffer from a rare form of severe combined immunodeficiency (SCID) called ADA-SCID. The trial marks one of the first successful uses of gene therapy since past trials of another form of SCID were shut down due to incidences of cancer amongst participants.
ADA-SCID is a rare genetic disorder that leaves children deficient in an enzyme called adenosine deaminase (ADA) which allows the body to fight outside contagions. Children with ADA-SCID can be treated with twice-weekly shots of adenosine deaminase or a bone marrow transplant. But the medicine is expensive and marrow transplants require a compatible donor and don't always work.
There were no available bone marrow donors for the ten children enrolled in the gene therapy trial. Instead, researchers removed marrow cells from the patients themselves and used a retroviral vector to give the cells working copies of the gene for adenosine deaminase. Then they injected the cells back into the patients. In most cases, the therapy was accomplished before the children reached the age of two. Results of the trial are reported two to eight years later. All ten patients were still alive, but two needed further treatment.
Gene therapy had a contentious history. While once hailed as the future of medicine it was nearly abandoned as a treatment technique after several early clinical trials went badly wrong, resulting in the death of at least one patient in the US. An earlier French trial to treat the most common form of SCID (X-SCID) was shut down after it was found that some participants had contracted cancer.
Thus far, none of the participants in this most recent study show any signs of cancer, or any other health problems, as a direct result of the gene therapy treatment. According to Dr Donald Kohn, a SCID expert at Children's Hospital Los Angeles and the University of Southern California, scientists are investigating in an effort to understand why treatment for one form of SCID should result in cancer and not another.
Sources and References
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