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.