Vaccine Stops Solid Cancer Tumor Growth in Mice

City of Hope
Tuesday, 18 March 2003

Research published in the current issue of The Journal of Immunology suggests that an existing, protein-producing vaccine could kill solid cancer tumors by supercharging the body's immune system.

While much of the current cancer vaccine research in humans focuses on individualized vaccines, this is the first that suggests a more generalized approach could be effective, said chief investigator Joshua Ellenhorn, M.D., division of Surgery, City of Hope Cancer Center.

"Laboratory mice immunized with a p53 protein-producing vaccine developed a brisk immune response, and immune cells from these animals were able to kill cancer cells in culture dishes in the laboratory," he said.

"In animals with growing tumors, we also saw the tumors regress and most of the them were cured of their tumors," Dr. Ellenhorn said.

The p53 protein, present in small amounts in all cells, controls the growth rate of normal cells. But about half of all cancer is the result of a mutation, which turns off a cell's ability to regulate growth, resulting in rapid growth of solid tumors.

Solid tumors are responsible for the most common forms of cancer, such as lung, breast, prostate and colon cancer.

Dr. Ellenhorn noted that on its own, the human immune response to the p53 protein is usually very weak and that the immune systems of cancer patients fail to destroy the p53 over-expressing cancer cells.

He said this might be because the human immune system sees p53 as a natural human protein against which it is unable to mount a rejection response. The vaccine in his team's research got around this problem by using higher doses than those used in other clinical trials.

The promising laboratory results are encouraging researchers to move to the next step of preparing and evaluating the vaccine for human cancer patients a few years from now.

The research took place in City of Hope's Laboratory of Vaccine Research, of which Don J. Diamond, Ph.D., is director. City of Hope co-investigators include Diamond; Jonathan Espenscheid, M.D.; Jeffrey Lamont, M.D.; Jeff Longmate, Ph.D.; Solange Pendas, M.D.; and Zhongde Wang, Ph.D.

The research work was supported by a grant from the National Institutes of Health, with additional funding from the Ed and Bea Wolfe Charitable Foundation and a gift from the Ella Fitzgerald Charitable Foundation.

For more information, or to contact City of Hope, see their website at: www.cityofhope.org