In a knee-jerk reaction, the Food and Drug Administration today suspended several US Gene Therapy experiments after a third child who underwent treatment in France developed cancer.
To add to their woes, panic stricken researchers are to be informed on Friday at the FDA's Cellular, Tissue and Gene Therapies Advisory Committee meeting in Rockville, that a monkey has died of cancer caused by a gene therapy experiment that was conducted six years ago.
Gene Therapy has been primarily used in X-linked severe combined immune deficiency, or X-SCID, which affects only boys. It disables their immune systems. A possible cure for this disease is an exact Bone Marrow transplant. This is very rarely done due to imperfect cross matching.
Researchers suggested an alternative whereby patients were given infusions of mouse viruses engineered to carry the immune system gene that was lacking. These viruses infect the hosts' immune system cells thereby delivering the required gene. However, the viruses sometimes disturb healthy genes which when disrupted cause cancer.
Alarm bells began ringing in Sept 2002 when a boy who had undergone gene therapy two years earlier developed leukemia. A second such case was reported in Dec 2002.An international suspension of the Gene therapy was put into place in the backdrop of these two cases. The 2 infants underwent a course of chemotherapy. One boy succumbed this October.
After revised safeguards were put into place, the trials began again last year. However, this latest development appears to have put a spanner into the works.
Alain Fischer of the Necker Hospital in Paris, the leader of the French study said "We want to continue, but of course there is a safety issue"
Mark Kay, a professor of pediatrics and genetics at Stanford University agreed with him "This is a devastating side effect," he said of the cancers, "But taking a disease that is pretty much fatal . . . if you can get a 60 or 70 percent cure rate, you have to balance that out."
