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Managing Cancer Care

How Immunotherapy Is Used to Treat Cancer

Immunotherapy is treatment that uses certain parts of a person’s immune system to fight diseases such as cancer. This can be done in a couple of ways:

  • Stimulating, or boosting, the natural defenses of your immune system so it works harder or smarter to find and attack cancer cells
  • Making substances in a lab that are just like immune system components and using them to help restore or improve how your immune system works to find and attack cancer cells

In the last few decades immunotherapy has become an important part of treating some types of cancer. New immunotherapy treatments are being tested and approved, and new ways of working with the immune system are being discovered at a very fast pace.

Immunotherapy works better for some types of cancer than for others. It’s used by itself for some of these cancers, but for others it seems to work better when used with other types of treatment.

What the immune system does

Your immune system is a collection of organs, special cells, and substances that help protect you from infections and some other diseases. Immune cells and the substances they make travel through your body to protect it from germs that cause infections. They also help protect you from cancer in some ways.

The immune system keeps track of all of the substances normally found in the body. Any new substance that the immune system doesn’t recognize raises an alarm, causing the immune system to attack it. For example, germs contain substances such as certain proteins that are not normally found in the human body. The immune system sees these as “foreign” and attacks them. The immune response can destroy anything containing the foreign substance, such as germs or cancer cells.

The immune system has a tougher time targeting cancer cells, though. This is because cancer starts when normal, healthy cells become changed or altered and start to grow out of control. Because cancer cells actually start in normal cells, the immune system doesn’t always recognize them as foreign.

Clearly there are limits on the immune system’s ability to fight cancer on its own, because many people with healthy immune systems still develop cancer:

  • Sometimes the immune system doesn’t see the cancer cells as foreign because the cells aren’t different enough from normal cells.
  • Sometimes the immune system recognizes the cancer cells, but the response might not be strong enough to destroy the cancer.
  • Cancer cells themselves can also give off substances that keep the immune system from finding and attacking them.

To overcome this, researchers have found ways to help the immune system recognize cancer cells and strengthen its response so that it will destroy them. In this way, your own body is actually getting rid of the cancer, with some help from science.

Types of cancer immunotherapy

There are several main types of immunotherapy used to treat cancer, and many are being studied. For more information about immunotherapy as a treatment for a specific cancer, please choose a cancer type.

  • Checkpoint inhibitors: These drugs basically take the ‘brakes’ off the immune system, which helps it recognize and attack cancer cells.
  • Chimeric antigen receptor (CAR) T-cell therapy: This therapy takes some T-cells from a patient's blood, mixes them with a special virus that makes the T-cells learn how to attach to tumor cells, and then gives the cells back to the patient so they can find, attach to, and kill the cancer.
  • Cytokines: This treatment uses cytokines (small proteins that carry messages between cells) to stimulate the immune cells to attack cancer.
  • Immunomodulators: This group of drugs generally boosts parts of the immune system to treat certain types of cancer.
  • Cancer vaccines: Vaccines are substances put into the body to start an immune response against certain diseases. We usually think of them as being given to healthy people to help prevent infections. But some vaccines can help prevent or treat cancer.
  • Monoclonal antibodies (mAbs or MoAbs): These are man-made versions of immune system proteins. mAbs can be very useful in treating cancer because they can be designed to attack a very specific part of a cancer cell.
  • Oncolytic viruses: This treatment uses viruses that have been modified in a lab to infect and kill certain tumor cells.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.

American Society of Clinical Oncology (ASCO). ASCO Annual Meeting 2019: Immunotherapy for lung cancer, gastrointestinal cancers and targeted therapy for breast cancer. Accessed at on December 19, 2019.

American Society of Clinical Oncology (ASCO). Understanding immunotherapy. Accessed at on December 19, 2019.

Bayer VR, Davis ME, Gordan RA, et al. Immunotherapy. In Olsen MM, LeFebvre KB, Brassil KJ, eds. Chemotherapy and Immunotherapy Guidelines and Recommendations for Practice. Pittsburgh, PA: Oncology Nursing Society; 2019:149-189.

Brodsky AN. Cancer immunotherapy: The year in review and a look at the year ahead. Cancer Research Institute. Accessed at on December 19, 2019.

Coventry BJ. Therapeutic vaccination immunomodulation: Forming the basis of all cancer immunotherapy. Ther Adv Vaccines Immunother. 2019; 1:7:2515135519862234. Accessed at on December 19, 2019.

DeMaria PJ, Bilusic M. Cancer vaccines. Hematol Oncol Clin North Am. 2019; 33(2):199-214.

DeSelm CJ, Tano ZE, Varghese AM, et al. CAR T-cell therapy for pancreatic cancer. J Surg Oncol. 2017; 16(1):63-74.

Gatti-Mays ME, Redman JM, Collins JM, et al. Cancer vaccines: Enhanced immunogenic modulation through therapeutic combinations. Hum Vaccin Immunother. 2017; 13(11):2561-2574. Accessed at on December 19, 2019.

Hafeez U, Gan HK, Scott AM. Monoclonal antibodies as immunomodulatory therapy against cancer and autoimmune diseases. Curr Opin Pharmacol. 2018; 41:114-121.

Hill JA, Giralt S, Torgerson TR, et al. CAR-T- and a side order of IgG, to go?- Immunoglobulin replacement in patients receiving CAR-T cell therapy. Blood Rev. 2019 [Accepted manuscript]. Accessed at on December 19, 2019.

Ling DC, Bakkenist CJ, Ferris RL et al. Role of immunotherapy in head and neck cancer. Semin Radiat Oncol. 2018; 28(1): 12-16.

Maeng H, Terabe M, Berzofsky JA. Cancer vaccines: Translation from mice to human clinical trials. Curr Opin Immunol. 2018; 51:111-122. Accessed at on December 19, 2019.

Mestermann K, Giavridis T, Weber J, , et al. The tyrosine kinase inhibitor dasatinib acts as a pharmacologic on/off switch for CAR T cells. Sci Transl Med.  [Abstract]. 2019; 11(499).

Myers DR, Wheeler B, Roose JP. mTOR and other effector kinase signals that impact T cell function and activity. Immunol Rev. 2019; 291(1):134-153.

National Cancer Institute (NCI). CAR T cells: Engineering patients’ immune cells to treat their cancers. Accessed at on December 19, 2019.

National Cancer Institute (NCI). Immunotherapy to treat cancer. Accessed at on December 19, 2019.

Russell SJ, Barber GN. Oncolytic viruses as antigen-agnostic cancer vaccines. Cancer Cell. 2018;33(4): 599-605. Accessed at on December 19, 2019.

Wraith DC. The future of immunotherapy: A 20-year perspective. Front Immunol. 2017:8:1668. Accessed at on December 19, 2019.

Last Revised: December 27, 2019

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