LOU WATERS, CNN ANCHOR: A quality control checkup has broken yet another gene therapy trial -- has brought the gene therapy trial to a halt. This one involves children terminally ill with cancer. CNN medical correspondent Eileen O'Connor joins us now with the story.</s>EILEEN O'CONNOR, CNN MEDICAL CORRESPONDENT: Well, Lou, it really was because of concern over gene therapy, over the past year, that many hospitals and universities involved in trials have been double- checking their quality control and compliance with federal guidelines. It was during such a review that a problem was discovered. Researchers at St. Jude's Children's Research hospital in Memphis, Tennessee contacted the Food and Drug Administration last Friday to tell them that some cancer vaccines that were genetically engineered and used on over two dozen young cancer patients may have been contaminated with the hepatitis C virus and HIV, the virus that causes AIDS. Both St. Jude's and the FDA caution that the tests used to determine this are preliminary screening tests that often result in what are called "false positives," indicating there is a problem when perhaps there isn't. In addition, the hospital contends: "The level of contamination was so low that even if it represented biologically active virus particles, the risk to the patients would be extremely low." Now, the FDA has now stopped the trial, both at Memphis and at Baylor College of Medicine in Houston. Officials there, who used seeds from the vaccine, say their vaccine components passed purity tests, including those for hepatitis C and HIV. FDA officials tell CNN that they are conducting more conclusive tests to determine if there was a risk to patients and are conducting an investigation into the procedures at the lab and in the clinical trial. The children treated in this trial, according to St. Jude's, had a recurrent form of cancer and no chance for survival. Four out of 20 are still surviving; only two may have received contaminated vaccines, and St. Jude's says there is no evidence that they were harmed -- Lou.</s>WATERS: All right, Eileen O'Connor, our medical correspondent in Washington.
FDA Investigating Possible Gene Therapy Contamination