Researchers use cancer vaccine as treatment

Remember that the earliest vaccines were made from weakened virus or bacteria cells. When a person got a measles vaccine, for example, her immune system recognized the vaccine cells as a virus, attacked them and then maintained a defense for that particular ailment.

Immunologist Doctor Larry Pease at Mayo Clinic says cancers aren't viruses.He says they are a growth of the body gone awry. A chromosome breaks, a protein gets switched on and left on

"And that makes the tumor grow," he continues. "And as a consequence of that it changes the nature of the cell and in a variety of different ways and its those changes in the cell that distinguish it from the body that could be attacked by the immune system."

The immune system doesn't recognize cancer cells as an illness. Pease says genetically your body is programmed not to attack itself, and cancer is part of the self. Pease, along with primary investigators Esteban Celis and Pilar Nava-Parada, found a way around this.

"The premise of the study was to develop a vaccine strategy that would be able to target the immune system and break self-tolerance so that the immune system could then combat the cancer," Pease says.

"The premise of the study was to develop a vaccine strategy that would be able to target the immune system and break self-tolerance so that the immune system could then combat the cancer."

In previous studies doctors have been able to get the body to attack itself, but it would then attack all of itself. Pease says Celis and Nava-Parada reasoned that they could make a vaccine that prompted the body to only look for cells with specific types of mutations.

The study used mice genetically predisposed to get breast cancer. Pease says it reflects the pathology of some women.

"Except for in this model it's even more severe than what would happen on a person," Pease says. "So in a person what would normally happen is that sporadic cells on the body would have this condition. And in these mice every breast tissue of these animals has the condition. But remarkably this treatment took care of that. And these animals were, all of the animals that were studied in this way were protected."

That is, they were all treated with the vaccine and did not die from the cancer. Pease says the vaccines are designed as a treatment and not as a prevention tool. And he believes they will likely work best with cancer in remission, when the body can look for remaining, sporadic cancer cells.

Researchers have been developing cancer vaccines for the last twenty years. The F.D.A. recently approved a prostate cancer vaccine. Clinical trials are currently underway for other cancer vaccines.

Pease says unlike most cancer treatments, this helps the body destroy the cancer, without harming anything else. And that's exciting.

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