New Hope in Cancer Vaccines Emerges as Novel Therapies Are Developed and Tested.

HOUSTON, Aug. 4 /PRNewswire/ -- Medicine can now prevent a host of diseases with a mere shot of vaccine. Polio and smallpox are almost non- existent, and mumps and chicken pox are rarely seen nowadays. And for the first time, the prospect of eradicating a specific cancer through vaccination is possible. The newly approved human papillomavirus (HPV) vaccine is designed to curb the 230,000 worldwide deaths due to cervical cancer, which is caused solely by HPV. And the hepatitis B virus, responsible for 70 percent of all liver cancer deaths, is also preventable with a vaccine.

Cancer researchers are working on the next era of vaccines designed to treat cancer that has already developed. These vaccines don't rev up the human immune system to attack an invading microbe, but prime the system to go after a unique biological tag found only on tumor cells.

For example, brain cancer researchers at The University of Texas M. D. Anderson Cancer Center are testing an experimental vaccine that homes to a protein studding the surface of glioblastoma cancer cells. It tricks the body into thinking this protein is foreign and infectious, which alerts killer immune cells. The same kind of strategy is producing very promising results in clinical trials at M. D. Anderson of vaccines for advanced myeloid leukemia as well as other forms of leukemia, aggressive lymphoma and melanoma.

Because of the preliminary nature of therapeutic cancer vaccines -- none has yet been approved for use anywhere in the world -- researchers can only describe their findings as "promising." But their hope in the therapy is clear. In fact, several M. D. Anderson vaccine clinical trials have shown strong anti-tumor activity and one produced the first clinical demonstration that a vaccine could produce complete molecular remission -- meaning, no biological evidence of cancer remained in some treated patients.

This wealth of cancer vaccine research at M. D. Anderson -- possibly the most varied and advanced in the nation -- has come about because of the strong interest from M. D. Anderson physicians and researchers in basic immunological science. They believe that the human immune system can be used against cancer, and that vaccines may represent the cutting edge of immunologic cancer treatment.

"Hypothetically, once the immune system has been sufficiently stimulated, it would be able to find and destroy every single tumor cell throughout the body," says Yong-Jun Liu, M.D., Ph.D., chair of the Department of Immunology and director of the Center for Cancer Immunology Research (CCIR).

"It could do this without destroying healthy tissue," he says. "That's the goal we strive every day for." Liu and other CCIR researchers believe that, ultimately, the best use of such vaccines will be to eliminate the minimal disease that remains after initial cancer therapy.

"When there is too much disease, the immune system is overwhelmed and a cancer vaccine may not be helpful," says Jorge Cortes, M.D., a professor in the Department of Leukemia. "But after patients have been treated, there is often a low level of disease, so our idea is that we can add a vaccine at that point to eliminate the cancer before it has a chance to grow back again."

"This is an exciting time in cancer research, given our increased understanding of the molecular nature of cancer and the immune response," says Patrick Hwu, M.D., chair of the Department of Melanoma. "Our ultimate success will likely depend on the rational combination of appropriate chemotherapies, targeted therapies, and immunotherapy, such as therapeutic cancer vaccines."

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