How Immunotherapy Works to Treat Colon Cancer

Immunotherapy is a type of cancer treatment that harnesses your own immune system to fight cancer. Immunotherapy treats many cancer types—including colon cancer. “We know that 5 percent or so of colon cancers will have a good response to immune checkpoint inhibitors,” says Elliot Newman, MD, chief of surgical oncology at Lenox Hill Hospital, Northwell Health System.

How Immunotherapy Works to Fight Cancer

Immunotherapies help the immune system recognize a tumor as something different than the normal tissues in the body. One of these immunotherapy approaches is a class of medications called checkpoint inhibitors.

“The reason they’re called immune checkpoint inhibitors is because our body has an immune system that has to be kept in check so it doesn’t destroy our cells,” says Dr. Newman. To do this, it uses “checkpoints”—which are proteins on immune cells that must be turned on (or off) to trigger an immune response.

Cancer cells sometimes use these checkpoints to essentially hide from and avoid being attacked by the immune system. “Cancer cells have learned to exploit that and have the ability to get around the immune checkpoint and flourish,” says Dr. Newman.

“What we learned by using checkpoint inhibitors is we can turn off this checkpoint inhibition, or the “breaks” in the immune system, and allow the immune system to work against the cancer cells,” says Dr. Newman. “And this therapy, for the right situation, can be very effective in controlling cancer and improving outcomes and survival.”

The Type of Colon Cancer Immunotherapy Can Treat

Immunotherapy isn’t appropriate for all colon cancer patients: It’s used to treat patients with advanced colorectal cancer, and only patients whose tumors have specific genetic mutations. A doctor determines if the tumor has those mutations by doing a biopsy.

Immunotherapy is still new as an option for cancer treatment, and it’s potential role for treating advanced colon cancer is still being discovered.

“Right now, the only place where we’ve seen some efficacy is in a small percentage of patients, approximately 5 percent of patients, who have a deficiency in what are known as mismatch repair (MMR) genes,” says Dr. Newman. “However, studies are ongoing to look at the role of these immune checkpoint inhibitors and other forms of immunotherapy in all types of colon cancer.”