Fighting colon cancer with immunotherapy

Colorectal cancer is the third most common cancer diagnosed in both men and women in the United States.

The American Cancer Society’s estimates that almost 101,420 new cases of colon cancer will be diagnosed in 2020.

While chemotherapy is still used to prevent recurrence of early stage colon cancer and treatment of advanced/metastatic colon cancer, immunotherapy is playing an increasing role in the treatment for certain groups of patients.

Immunotherapy is the use of medications that utilize a person’s own immune system to better recognize and destroy cancer cells. It can help treat some people with advanced colorectal cancer as well as certain other cancers that respond to manipulation of one’s own immune system.

An important part of the immune system is its ability to keep itself from attacking the body’s normal cells. To do this, it uses “checkpoint” proteins on immune cells, which act like switches that turn on or off to start an immune response. Certain cancers use these checkpoints to keep the immune system from attacking them. New immunotherapy agents that target these checkpoints hold a lot of promise as cancer treatments.

Drugs called checkpoint inhibitors can be used for patients whose colorectal cancer cells have tested positive for specific gene changes, such as a high level of microsatellite instability (MSI-H) or changes in one of the mismatch repair (MMR) genes. These drugs are used for patients whose cancer is still growing after treatment with chemotherapy. They might also be used to treat people whose cancer can’t be removed with surgery, has come back after treatment or has spread to other parts of the body (metastasized). These drugs are effective mostly in those whose tumors test positive for MSI-H.

Pembrolizumab (Keytruda) and nivolumab (Opdivo) are examples of checkpoint inhibitors that target PD-1, a protein on immune system cells called T cells that normally help keep these cells from attacking other cells in the body. By blocking PD-1, these drugs boost the immune response against cancer cells. These drugs are given as an intravenous (IV) infusion every two or three weeks.

Even though checkpoint inhibitors can be very effective and are exciting treatment options for those suffering from colon and certain other cancers, serious side effects can potentially occur. These drugs work by basically removing the brakes from the body’s immune system. Sometimes the immune system starts attacking other parts of the body, which can cause serious or even life-threatening problems in the lungs, intestines, liver, hormone-making glands, kidneys or other organs. Therefore, we closely monitor these side effects during clinic visits via physical exam and lab assessment.

Clinical trials are underway to see if these checkpoint inhibitors can be used in combination with chemotherapy in early stage disease (stage III) following surgery to prevent recurrence and in advanced stage (stage IV) to see if these drugs can be used early in the course of the treatment, either alone or in combination with chemotherapy to improve survival.

Dr. Jewel Johl is a board certified medical oncologist and hematologist with Diablo Valley Oncology & Hematology Medical Group. He has expertise in treating all forms of cancer and blood disorders and has a particular interest in the treatment of gastrointestinal cancers and colorectal cancers. For more information, call 925-677-5041 or visit dvohmg.com