Peptide could be clue for cancer vax

In a recent study, 100 percent of mice vaccinated with a peptide remained tumor-free for at least 60 days after inoculation with colon cancer cells. And scientists from the University of Colorado School of Medicine and National Jewish Health say this method could be a key in developing vaccine for a range of cancers.

Scientists have known that there are T-cells inside tumors, meaning the body does have a natural--albeit mild--immunity to cancer. The T-cells inside tumors recognize antigens on the surfaces of tumor cells, but don't bind to them strongly enough to sound an alarm or initiate a robust immune response.

Jill Slansky, associate professor in the Integrated Immunology Department between National Jewish Health and the University of Colorado School of Medicine, hypothesized that previous vaccine candidates were unsuccessful because they did not bind strongly enough to the T-cells found inside tumors. So, she, structural biologist John Kappler, and postdoctoral fellow Kimberly Jordan designed peptide vaccines that resemble naturally occurring antigens but bind more strongly to the T-cells found inside tumors.

"Our theory about the importance of the T-cell peptide bond was correct, but we learned that the peptides must also stimulate T-cells that cross react with the existing antigens and produce a large population of activated T-cells," Kappler says in a statement. The results were published in the Feb. 16 issue of the Proceedings of the National Academy of Sciences.

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