This rare genetic disease occurs when children are born with a deficiency of an enzyme called adenosine deaminase, which is essential to the functioning of the immune system. As a result, ADA-deficient children are prone to repeated and serious infections. Even the most minor of viral illnesses can be life threatening. The ADA gene therapy trial began in September 1990. Two children were treated and the results have been promising.
Scientists researching the treatment of cancer with gene therapy have three basic approaches.
One way is to genetically alter a person's immune cells that are already naturally targeted to kill cancer cells. By arming immune cells with cancer-fighting genes, it is hoped they could more forcefully attack the cancer. Clinical trials along these lines are in progress for the treatment of melanoma. Another method is to take cancer cells from the body and alter them genetically so that they elicit a strong immune response. These cells can then be returned to the body to act as a type of cancer vaccine.