In their work, the authors removed the innards of the virus and substituted instead a gene for the carcinoembryonic antigen (CEA). This immune system biomarker is overproduced in many different types of cancer.
The vaccine was then administered multiple times over a period of three months to 28 patients with advanced, recurrent forms of lung, colon, breast, appendix or pancreatic cancer. The participants had already failed several rounds of standard chemotherapy.
Five patients displayed a response to the therapy: Two who had already been in remission stayed in remission; two patients saw their cancers stabilize; and a liver lesion in one patient with pancreatic cancer was no longer evident.
The responses tended to occur in patients with smaller tumors and in those receiving higher doses of the vaccine.
The alphavirus-based vaccine also managed to evade the immune system's regulatory T cells, which could have shut down the body's immune response, the researchers said.
Although T cell levels were elevated in some patients, the vaccine was able to get around them.
Co-authors included employees from Alphavax, which develops new vaccine technology. The study was partially supported by the U.S. National Cancer Institute.
There's more on cancer vaccines at the U.S. National Cancer Institute.
SOURCES: Michael Morse, M.D., associate professor, medicine, Duke University Medical Center; Adam Cohen, M.D., assistant professor, medical oncology, Fox Chase Cancer Center, Philadelphia; Aug. 2, 2010, Journal of Clinical Investigation, online
All rights reserved