Preventive Immunotherapy for Colorectal Cancer

In the Pipeline: Preventive Immunotherapy
for Colorectal Cancer

Your immune system serves as the front line in your body's defense against illness. Its job is to detect foreign intruders, like bacteria or viruses, and to then manufacture the antibodies necessary to destroy them. And it does this quite well -- except when the intruder is cancer.

The problem is that cancer cells are like double agents. They start off as normal, healthy cells, but when they become cancer cells, they act like foreign invaders. And even though they are doing things cells are not supposed to do, your immune system continues to perceive them as the normal cells they used to be.

But what if it were possible to teach your immune system that cancer cells are just like any other foreign invader that needs to be sought out and destroyed? That's the question cancer researchers have been pursuing. And they are now getting closer to finding the answer.

Preventive Immunotherapy

Most likely, you've received a number of preventive vaccines over your lifetime. And they've been incredibly effective at controlling diseases like measles and chickenpox and at virtually eradicating others such as smallpox and polio. All of these vaccines were designed to do the same thing: introduce your immune system to a virus so that it would know how to fight off the virus if it ever encountered it again.

The same strategy has been effective in fighting off some virus-related cancers: The hepatitis B vaccine, which helps prevent infection with the hepatitis B virus, reduces the risk of liver cancer, and Gardasil, the vaccine against human papillomavirus, reduces the risk of cervical cancer. But will a vaccine for colorectal cancer prevention be next in line?

That is the hope of a group of researchers at the University of Pittsburgh. They are currently conducting a phase II trial of a vaccine, called MUC1 poly-ICLC, in people at high risk for developing colorectal cancer.

MUC1 is a cell protein that is produced in large amounts by precancerous polyps and colorectal cancer tumors. The vaccine teaches the immune system that the MUC1 protein is a foreign invader and that it needs to destroy any cells that are harboring it. Poly-ICLC is a drug used to boost the body's response to vaccination.

The researchers hope that by getting the immune system to go after these cells, the vaccine will be able to prevent polyps from turning into colorectal cancers and to keep the polyps from recurring. Interest in MUC1 for colorectal cancer stems, in part, from research showing that people with pancreatic cancer or breast cancer who naturally produce antibodies against the MUC1 vaccine live longer than those who don't produce them.

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December 15, 2010
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