Immunotherapy for Colorectal Cancer

Immunotherapy is the use of medicines to help a person’s own immune system better recognize and destroy cancer cells. Immunotherapy can be used to treat some people with advanced colorectal cancer.

Immune checkpoint inhibitors

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 need to be turned on (or off) to start an immune response. Cancer cells sometimes use these checkpoints to keep the immune system from attacking them. But drugs that target these checkpoints hold a lot of promise as cancer treatments.

Pembrolizumab (Keytruda) and Nivolumab (Opdivo) are drugs that target PD-1 (programmed cell death protein 1). PD-1 is a protein found on immune system cells called T cells. It normally helps keep these cells from attacking "good" cells in the body.

Pembrolizumab and nivolumab block the cancer cells' ability to attach to PD-1, so, the immune system can then "see" the cells as "bad." This boosts the immune response against the cancer cells and can shrink some tumors or slow their growth.

These drugs can be used for people 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. The drugs are used for people 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 (recurred) after treatment, or has spread to other parts of the body (metastasized).

Pembrolizumab (Keytruda) is given as an intravenous (IV) infusion. Treatment takes about 30 minutes and is given every 3 weeks.

Nivolumab (Opdivo) is given as an (IV infusion) that takes 1 hour. It's given every 2 weeks.

Possible side effects

Side effects can include:

  • Fatigue
  • Fever
  • Cough
  • Shortness of breath
  • Itching
  • Skin rash
  • Nausea
  • Loss of appetite
  • Diarrhea
  • Constipation
  • Muscle and/or joint pain

Other, more serious side effects occur less often. Checkpoint inhibitors work by basically removing the brakes on 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.

It’s very important to tell your cancer care team about new side effects right away. Let them know about any changes you notice. If serious side effects do occur, treatment may need to be stopped and you may get high doses of steroids to suppress your immune system.

More information about immunotherapy

To learn more about how drugs that work on the immune system are used to treat cancer, see Cancer Immunotherapy.

To learn about some of the side effects listed here and how to manage them, see Managing Cancer-related Side Effects.

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master's-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Bristol-Myers Squibb. Opdivo. Accessed at on February 14, 2018.

Merck Sharp & Dohme Corp. Keytruda. Accessed at on February 14, 2018.

National Comprehensive Cancer Network, Clinical Practice Guidelines in Oncology (NCCN Guidelines®), Colon Cancer, Version I.2018 -- January 18, 2018. Accessed at on February 14, 2018.

National Comprehensive Cancer Network, Clinical Practice Guidelines in Oncology (NCCN Guidelines®), Rectal Cancer, Version 4.2017 -- January 18,
2018. Accessed at on February 14, 2018.

Overman MJ et al. Nivolumab in patients with metastatic DNA mismatch repair-deficient or microsatellite instability-high colorectal cancer (CheckMate 142): an open-label, multicentre, phase 2 study. Lancet Oncol. 2017 Jul 19. 

US Food and Drug Administration. FDA approves first cancer treatment for any solid tumor with a specific genetic feature. [News Release] 2017. Accessed at on May 24, 2017.

US Food and Drug Administration. FDA grants nivolumab accelerated approval for MSI-H or dMMR colorectal cancer. [News Release] 2017. Accessed at on August 23, 2017.

Last Medical Review: February 21, 2018 Last Revised: February 21, 2018

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