Blood Cancer &
 Leukemia

Leukemia Cancer News - Return to Menu

Gene therapy studies suspended after death

French experiment worries U.S. experts

By Thomas H. Maugh II
Tribune Newspapers: Los Angeles Times
March 4, 2005 - Federal authorities have suspended three gene therapy experiments after news that a third child in a similar French study has developed leukemia and that one of the three has died.

A Food and Drug Administration advisory panel is to meet in suburban Washington on Friday in an effort to determine whether the French cases are an isolated incident caused by the specific gene being used in the therapy or a precursor of problems that will affect all gene therapy attempts.

Experts don't expect an immediate consensus from the advisory panel, but there appears to be a growing feeling among researchers that the problem is of limited scope and reflects the combination of the virus and gene used by the French. Experiments using other genes have been free of adverse effects.

Most of the researchers involved will be gathering in Washington on March 15 for a separate meeting sponsored by the National Institutes of Health Recombinant DNA Advisory Committee. They are scheduled to discuss their results to date. Despite the three leukemia cases, the results have been promising.

The experiments in question have involved treatments for severe combined immunodeficiency disease, or SCID, a potentially fatal genetic disorder that leaves its victims susceptible to life-threatening infections. The best-known example of the disease was David, the Houston "Bubble Boy" who lived for 12 years in a sterile enclosure to keep infections out.

Dr. Alain Fischer of Necker Hospital in Paris has been treating patients with so-called X-linked SCID, which is caused by a defective gene called GammaC. Fischer put a healthy form of the gene in a modified mouse leukemia virus, which was used to insert the gene into embryonic blood cells that are then infused into the patient.

Fischer has treated 17 patients, and virtually all have shown major improvement--if not a cure. But two years ago, Fischer said that two of the patients developed leukemia, presumably as a result of the treatment.

The FDA suspended 27 gene therapy trials in the United States but eventually allowed them to proceed again after concluding that there were special circumstances in the cancer victims. Both were below the age of 2 and received large doses of cells.

In recent weeks, Fischer revealed that one of the two original leukemia victims died of the disease and that a third child apparently contracted it. That child was older than the first two and received a lower dose of altered cells.

The FDA has temporarily shut down three studies examining treatments for SCID.

One of the studies is run by Dr. Harry Malech and Dr. Jennifer Puck of the National Institute of Allergy and Infectious Diseases. A second is run by Dr. Donald Kohn of the Keck School of Medicine at the University of Southern California. The third is run by Dr. Kenneth Weinberg of Keck.

FDA panel says proceed cautiously up to two gene therapy trials

Author : Martin Booth
News Category : Health

2005-03-06 - There were no surprises at the Food and Drug Administration advisory panel committee meeting to review the gene therapy experiments. Two trials being held at the National Institutes of Health and at the University of Southern California have been asked to see that all avenues of treatment be explored before continuing the experiments.

However, the FDA did allow one experiment that was being carried out at the USC since the disease in question is a variation of SCID that differs from the strain being treated by French researchers.

Dr. Mahendra Rao, chairman of the FDA's Cellular, Tissue and Gene Therapies Advisory Committee, said that the meeting was held in the backdrop of a third child developing leukemia in France.
However, he said that the FDA had not set a schedule to act on the panel's recommendations.

Day Care at Early Age May Cut Leukemia Risk

By Steven Reinberg
HealthDay Reporter

FRIDAY, April 22 (HealthDayNews) -- Children who attend day-care centers regularly during their first few months of life are less likely to develop leukemia than children who don't, British researchers report.

The scientists believe their finding bolsters the theory that increasing exposure to common infections during the first year of life may decrease the risk of developing acute lymphoblastic leukemia.

"Our results provide further support that social activity with other infants and children during the first few months of life protects against subsequent risk of acute lymphoblastic leukemia," the researchers state in the April 22 online issue of the British Medical Journal.

One expert finds the study intriguing but of potentially limited value. "These are interesting and provocative findings," said Dr. Stephen Earl Sallan, a pediatric oncologist at Children's Hospital Dana Farber Cancer Institute, in Boston.

But Sallan also noted that parents whose children are not in these settings might think their children have an increased risk of developing leukemia. "This is not so," he said.

The overwhelming majority of children will never develop leukemia or any other malignancy, Sallan said. "It is only that they have a statistically significantly increased risk of developing leukemia compared to those in 'the right' social setting," he said.

"My guess is that this [study] will allay the guilt of some families who are ambivalent about sending their young children to busy day-care settings, and initiate the guilt of those who choose not to do so. Such is life," Sallan added.

In the study, the team collected data on 6,305 children without cancer, and 3,140 with cancer (1,286 had acute lymphoblastic leukemia). The children were between 2 and 14 years of age.

The investigators found that as levels of social activity increased, the risk of acute lymphoblastic leukemia decreased. The greatest reduction in risk was 69 percent, seen among children who went to day care during the first three months of life.

"Whether early exposure to one or more specific infections, or to a spectrum of non-specific agents, protects against diseases remains to be clarified," the researchers wrote. "Nevertheless, we conclude that some degree of early exposure to infection seems to be important for child health."

Another expert is also not sure if the data is useful. "When I read this, I say, 'What are we going to do with this information?' " said Dr. Herman Kattlove, a medical oncologist and spokesman for the American Cancer Society.

Kattlove said that maybe one can find a specific infection that is protective. It might be possible to identify that infection and then find ways of preventing acute lymphoblastic leukemia, he noted.

"Although we focus a lot on childhood leukemia, there aren't a lot of cases," Kattlove said. In the United States, there are some 2,000 new cases of acute lymphoblastic leukemia each year.

"Most of these cases are cured," Kattlove said. Given that the five-year survival rate is at 85 percent, he wondered, "Would anyone want to spend the research time and money to follow up [this study] for very little gain? The answer would probably be no."

More information

The American Cancer Society can tell you more about leukemia.

Site Map | Acute Myelogenous Leukemia