NEW YORK -- Scientists are reporting the first clear success with a new approach for treating leukemia -- turning patients' own blood cells into assassins that hunt and destroy cancer cells.
It's only been done in three patients, but the results are striking: Two appear cancer-free up to a year after treatment, and the third is improved but still has some cancer. Scientists are preparing to try the gene therapy technique on other kinds of cancer.
"It worked great. We were surprised it worked as well as it did," said Dr. Carl June, a University of Pennsylvania gene therapy expert. "We're just a year out now. We need to find out how long these remissions last."
June led the study published Wednesday by two journals, New England Journal of Medicine and Science Translational Medicine.
It involved three men with very advanced cases of chronic lymphocytic leukemia, or CLL. The only hope for a cure now is bone-marrow or stem-cell transplants, which don't always work and carry a high risk of death.
Earlier attempts at genetically modifying bloodstream soldiers called T-cells have had limited success; the modified cells didn't reproduce well and quickly disappeared.
June and his colleagues made changes to the technique, using a novel carrier to deliver the new genes into T-cells and a signalling mechanism telling the cells to kill and multiply. That resulted in armies of "serial killer" cells that targeted cancer cells, destroyed them, and went on to kill new cancer as it emerged.
It was known T-cells attack viruses that way, but this is the first time it's been done against cancer, June said.
Blood was taken from a patient and T-cells removed. After they were altered in a lab, millions were returned to the patient in three infusions.
The researchers described the experience of a 64-year-old patient in detail. There was no change for two weeks; then he became ill with chills, nausea and fever. He and the other two patients were hit with a condition that occurs when a large number of cancer cells die at the same time -- a sign the gene therapy is working.
The main complication seems to be this technique also destroys some other infection-fighting blood cells; the patients have been getting monthly treatments for that.
Penn researchers want to test the technique in leukemia-related cancers and pancreatic and ovarian cancer, June said. Other institutions are looking at prostate and brain cancer.
-- The Associated Press