Two Ohio girls who underwent the first attempt at human gene therapy in 1990, to treat a deadly immune deficiency, are now healthy and have stronger immune systems, according to a study being published Friday.
Improvements in the patients, now ages 9 and 14, have been reported earlier at scientific meetings. But the study in today's issue of the journal Science, documenting how long the therapy lasts and its potential benefits, is the first published account of the historic trial.Before the therapy, one of the girls could not leave her house for fear of infection, and the other was constantly sick. Now, Ashanthi DeSilva, 9, from a Cleveland suburb, and Cynthia Cutshall, 14, from Canton, live nearly normal lives, going to school and playing outdoors.
Considering it was the first human gene therapy, "We're absolutely thrilled. We couldn't have asked for a better outcome," said Dr. R. Michael Blaese, chief of the clinical gene therapy branch of the National Institutes of Health's human genome research center, and lead author of the study.
But, Blaese added, "This is not a definitive treatment for anybody yet."
Other researchers also welcomed the study, as well as two other new studies of gene therapy and so-called ADA deficiency, one also in today's Science and the other in this month's Nature Medicine. However, they cautioned that many questions have yet to be answered before such therapy can be widely considered.
Already, about 175 study protocols, or treatment guidelines, have been approved worldwide for gene therapy for such diseases as arthritis, cancer and AIDS, according to Dr. W. French Anderson, one of the authors of the NIH study.
ADA deficiency is considered one of the easiest genetic disorders to try to treat with gene therapy.
The biggest question about the NIH study for Dr. David G. Nathan president of the Dana-Farber Cancer Institute, concerns the gene therapy approach used: Taking T cells, a form of white blood cell, from patients; expanding them in the test tube; adding a harmless virus to carry the missing gene to make the protein ADA; and reinfusing the cells into the patient.
"It's a sort of high-risk procedure," said Nathan, who is taking a slower, more conservative approach to human gene therapy. Nathan has been named principal investigator for a five-year NIH grant to study a different approach that would make the genetic correction in the bone marrow's stem cells.