"That's exactly what I'd like to eventually see -- the vaccine used earlier in the disease process before other [toxic drugs] that can damage the immune system," he said. "I think it makes more sense, when the immune system is more likely to overcome a lower tumor burden. Until recently we haven't seen a lot of substantial clinical impact of vaccines . . . I think this gives us a better level of confidence."
Among the 12 study participants with breast cancer, the median time before the disease continued to progress was 2.5 months and the median overall survival was 13.7 months. For the 14 patients with ovarian cancer, the median time to progression was two months and the median overall survival was 15 months.
Side effects from the vaccine were exceedingly mild, with minor injection-site reactions the most common problem reported.
The PANVAC vaccine, containing certain genes that encourage the immune system to recognize and destroy tumor cells, was previously studied in 70 patients with advanced colorectal cancer, Gulley said. While the time before disease progression was similar between patients who did and did not receive the vaccine, the overall survival time in the vaccine group was "strikingly better," he noted.
"This is an exciting step forward," said Dr. David Fishman, a professor of obstetrics, gynecology and reproductive science at Mount Sinai Medical Center in New York City. "The ultimate goal would be to identify unique proteins in an individual patient's cancer and use vaccines unique to that patient."
The U.S. National Cancer Institute has more information on cancer vaccines.
SOURCES: James L. Gulley, M.D., Ph.D., director, clinical trials group, deputy chief, Laboratory of Tumor Immunology and Biology, U.S. National Cancer Institut
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