FDA Suspends Gene Therapy Experiments After Cancers Reported
FDA has "temporarily suspended" three gene therapy experiments for a severe immune system disorder following news that a third child in a similar French study has developed leukemia, the Los Angeles Times reports. Seventeen French patients with X-linked severe combined immunodeficiency disease have undergone a treatment that uses a modified mouse leukemia virus to replace a defective gene with a healthy one.
Although "virtually all" of the patients "have shown major improvement if not a cure" from the disease, three have developed leukemia within several years of treatment and one has died from the cancer, the Times reports. Concern over cancer increased last month when the National Heart, Lung and Blood Institute revealed that one of 42 monkeys that have undergone the same gene treatment has died of cancer (Maugh, Los Angeles Times, 3/4). The monkey was given gene therapy treatment six years ago, drawing concerns from researchers about the "long-term as well as near-term risks" of the treatment from researchers, the Washington Post reports. Researchers have said the mouse virus can disturb healthy genes, including genes that can trigger cancer (Weiss, Washington Post, 3/4).
According to the Times, FDA has not formally announced a suspension of the three trials, but each of the trials will have to revise their consent forms to provide more thorough information about potential risks of the treatment. The Times reports that the trials essentially "will have to go through most of the approval process a second time." An FDA advisory panel is scheduled to meet Friday in an effort to determine whether the French cases were caused by the specific gene being treated or if all gene therapy attempts could face similar problems.
A meeting on March 15 of the NIH Recombinant DNA Advisory Committee will discuss the results of gene therapy treatments (Los Angeles Times, 3/4). Several scientists said genetically modified "lentiviruses," including the HIV virus, could offer superior results to the mouse virus "in part because they appear less likely to trigger the kind of cell replication that adds up to cancer," the Post reports.
Alain Fischer, lead researcher of the French study at Necker Hospital in Paris, said, "There is a future in gene therapy. [The patients] can cope with infections. That tells us efficacy is there."
Mark Kay, professor of pediatrics and genetics at Stanford University and president-elect of the American Society of Gene Therapy, said cancer is "a devastating side effect. But taking a disease that is pretty much fatal ... if you can get a 60% or 70% cure rate, you have to balance that out" (Washington Post, 3/4).