Post a Comment        E-mail To A Friend        Join The List

UGA Team Makes Progress On Cancer Vaccine

by T.O. Lawrence
11/14/2007

For years, scientists have been searching for a cancer vaccine which would allow the body to utilize its own immune system in the identification and elimination of the disease. In recent months, researchers at the University of Georgia Cancer Center headed by Franklin Professor of Chemistry Geert-Jan Boons have discovered a means to encourage such a response.

According to county nurse manager Marcia Massengill, vaccines are generally prophylactic, meant to prepare the body for an attack by an outside invader. By introducing weakened or dead viral cells to the body, the body’s immune system is able to identify the disease, attack it and prepare itself with defenses against future infection. The difference with a cancer vaccine is that cancer cells are already part of the body and therefore are not recognized as dangerous by the body's defenses.

“The body cannot identify the tumor cells as invaders because they are not. They are host cells that have undergone change. For this reason, the immune system does not recognize them as threats but rather as regular cells,” said Boons.

Though the body might not recognize the change that takes place in tumor cells, scientists do. A distinct mutation in the surface sugars of the cancer cell distinguishes it easily from other healthy cells. Boons’ vaccine labels these tumor cells as invaders and in effect “tricks” the immune system into reacting against them.

Though researchers have been aware of this change in surface carbohydrates since the 1970s, they had been unable to create a substance which incites attack exclusively on the cancer-associated cells. Earlier trials included a linker protein which could bond to the cancer-associated carbohydrate but resulted in the immune system attacking the protein rather than the cancer cell itself.

In 2005, however, Boons and his team, funded by the National Cancer Institute, had created an entirely synthetic vaccine which stimulated an immune response towards the tumor-cells alone. Over the next two years, the vaccine was tweaked, recalibrated and eventually optimized into its current form in order to encourage higher antibody levels and a stronger immune response.

“We wanted to incite as much immune response as possible in order to ensure the destruction of cancer cells,” explained Boons. “As a result, we developed a three-part vaccine which approaches the disease on all levels.”

The three-part biological blitzkrieg unfolds like this: A tumor-associated carbohydrate activates the immune systems B cells which create antibodies and attracts other immune system cells. A part of a protein incites the body’s T cells to action which defend the B-cells as they manufacture antibodies. A final linker molecule derived from bacteria is included to alert the body to danger and encourage the production of cytokines (generalized immune-system components).

Though the results have only been proven on laboratory mice, the implications are profound. A vaccine of this sort would be effective against breast, prostrate and pancreatic cancer as a post-surgery addition. Once the primary tumor is removed, the vaccine may locate, identify and encourage elimination of any straggling cells which were not removed by traditional methods.

“Manual and chemical removal of stray cancerous cells is very difficult and dangerous,” said American Cancer Society researcher Len Lichtenfeld. “If the vaccine is as effective as they hope, it could eliminate the need many types of traumatic post-surgery therapy including some forms of chemo.”

Only time will tell if this is possible as Boons hopes to move to human trials within the year. In the meantime, he and his team are researching the specific cytokines and antibodies most effective in immune response in order to further optimize the vaccine for clinical use.