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TUESDAY, March 2 (HealthDayNews) -- Using a vaccine that targets an altered gene known to increase breast cancer risk, followed by a booster vaccine a week later, helped halt cancer and reversed cancerous lesions to an earlier stage in animals, Italian scientists report.

Experts caution the research is in its early stages and may not work in humans. The study appears in the March 1 issue of the Journal of Clinical Investigation.

A team led by Dr. Federica Cavallo of the University of Turin, Italy, worked with mice who over-expressed the HER-2/neu oncogene. An oncogene is an altered gene that develops into a cancerous one, and the over-expression of Her-2/neu is found in up to 30 percent of breast cancers as well as other types of cancers. This makes it a popular target for immunologic research.

The combined vaccine approach included a primary vaccination with self-replicating DNA molecules, or plasmids, which encoded portions of the oncogene's protein, rp185neu, to inhibit the growth of precancerous lesions. Then a booster vaccine was given a week later with cells expressing this protein and also engineered to release a kind of interferon, which boosts immune function.

The combination approach kept 48 percent of the mice tumor-free. At 22 weeks, the tumor-free mice were not distinguishable from those of 10-week-old mice who were untreated.

Vaccines for breast cancer is still considered an experimental idea. While traditional vaccines aim to prevent disease, some breast cancer vaccines are designed to treat or cure cancer that's already present. The goal is to stimulate an antibody response by injecting weakened or dead elements of breast cancer cells. Once the antibodies attack and destroy cancer cells, it is hoped they will continue to circulate and attack any new cancer cells that appear.

Several breast cancer vaccines are in development in the United States and overseas. If they bear out, researchers say it might be possible someday to give women at high risk for breast cancer a vaccine to eliminate or reduce the chances they will get the disease.

"The concept is wonderful," says Dr. Herman Kattlove, a spokesman for the American Cancer Society. "But it's an early study."

In the war on cancer, "some kind of immunologic method will probably be necessary," he says. "Vaccines are a way to achieve this." But the research is much too preliminary to be considered promising yet for humans, he cautions. Any application of the new research, he says, is no doubt several years away.

More information

Learn about breast cancer prevention at the National Cancer Institute, while a page on using the immune system to fight the disease is at breast cancer.org.

(SOURCES: Herman Kattlove, M.D., spokesman, American Cancer Society, Los Angeles; March 1, 2004, Journal of Clinical Investigation )

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