Promise and Peril in Gene Therapy Human Trials
Feb. 25, 2000 (Boston) -- The death last September of an 18-year-old student who was enrolled in a gene therapy clinical trial has raised troubling questions about patient safety in experiments using humans. But equally troubling, investigators say, is the prospect that safety fears could jeopardize support for research into life-saving experimental therapies.
"I'm not a gene therapy person, but I am a person who is interested in having science help the human condition," says Ron DePinho, MD, an American Cancer Society research professor at the Dana Farber Cancer Institute at Harvard Medical School in Boston. "It's very important to keep in mind that we would not be in the position we would be in now, with 70% of kids surviving cancer, were it not for all of the clinical trials of the past four decades. Many kids were subjected to treatments that didn't end up working, and they ended up dying."
DePinho and other researchers are worried that recent news reports about deaths or medical complications in patients who were enrolled in gene therapy trials could make regulatory and funding agencies, such as the FDA and the National Institutes of Health, skittish about approving new trials. This could scare off people who might otherwise benefit from experimental therapies. In addition, concerns about the future of genetics research could dissuade fresh young talent from entering the field, seasoned researchers warn.
After 18-year-old Jesse Gelsinger died in September 1999, researchers at the University of Pennsylvania were forced to halt a trial of gene therapy that used a modified cold virus to deliver genes into the body. These genes had the potential to correct the underlying defect in Gelsinger and other patients with a rare disease called ornithine transcarbamylase deficiency.
This disease is caused by a genetic deficiency that interferes with the body's ability to remove ammonia from the blood stream. When ammonia builds up in the body, it can cause irreversible brain damage or death if it is not treated.
According to a written statement from the University of Pennsylvania, "The most significant factor in [Gelsinger's] death was oxygen deprivation brought on by Adult Respiratory Distress Syndrome (ARDS) -- a severe lung dysfunction not seen previously in any study animals or clinical trial volunteers. Although analysis of the findings is ongoing, it is the belief of the investigators that the injection of the [modified virus] triggered the sequence of events that led to Mr. Gelsinger's death."
Reports about the Pennsylvania studies' suspension and of genetic therapy trials for the blood-clotting disorder hemophilia conducted at Beth Israel Hospital in Boston prompted President Clinton on Feb. 8 to order an expedited review of gene therapy research guidelines.
"Like many Americans, I have been extremely concerned about reports that some families involved in trials of experimental gene therapies have not been fully informed of the risks, and that some scientists have failed to report serious side effects from these trials," Clinton said at a news conference.