What Is Immunotherapy? A Plain-Language Guide

If your care team has brought up immunotherapy, you probably have questions. Here's a simple look at what it is, the main types, and what to expect.

What is immunotherapy?

Immunotherapy is a type of cancer treatment that helps your immune system fight cancer.¹ Chemotherapy works against cancer cells (and some healthy cells) directly. Immunotherapy works with your immune system to kill cancer cells or limit their growth.²

Immunotherapy can lead to long-lasting responses, but it doesn't work for every cancer or every person.²

The main types

The National Cancer Institute lists five main types: checkpoint inhibitors, T-cell transfer therapy, monoclonal antibodies, treatment vaccines and immune system modulators.¹ Here's how four of them work.

• Checkpoint inhibitors. Some tumors make large amounts of a protein called PD-L1. It attaches to PD-1 on T cells, a kind of immune cell, and keeps them from killing the cancer.³ Checkpoint inhibitors block that "off" signal so T cells can kill cancer cells.³ They're approved for some people with many cancer types, including breast, bladder, lung, liver, kidney, stomach and skin cancers such as melanoma.³
• Monoclonal antibodies. These are immune system proteins made in a lab. Some mark cancer cells so the immune system can better find and destroy them.⁴
• Cancer treatment vaccines. Unlike vaccines that help prevent cancer, these are for people who already have cancer. They strengthen the body's natural defenses against it.⁵
• T-cell transfer therapy. This type takes immune cells from your own tumor, picks the ones most active against your cancer, and may change them in a lab before giving them back through a vein.¹ CAR T-cell therapy is one example. It alters the genes in a person's T cells to help them attack cancer.⁶

How it's given

• Most types are given as an infusion through an IV. Some are injected into the fatty tissue just under the skin.²
• Other forms include pills, a cream for very early skin cancer, and treatment placed directly into the bladder.¹
• Treatment usually happens at a doctor's office, clinic or hospital outpatient unit, so you don't spend the night.¹
• Doses may be daily, weekly or monthly. Some treatments come in cycles: a period of treatment followed by a period of rest.¹

How your team checks if it's working

Your doctors will use physical exams, symptom checks, blood tests and scans to measure your tumor and look for changes in your blood work.¹

Biomarker tests on your cancer play a role, too. Some immunotherapies may only work for people whose cancers have certain biomarkers.⁸

Possible side effects

When your immune system is revved up to act against cancer, it can also act against healthy cells and tissues.⁷ Side effects can happen at any point during and after treatment.⁷ They may include:⁷

• Flu-like symptoms, such as fever, chills, weakness and muscle aches
• Tiredness, nausea or vomiting, and diarrhea
• Pain, swelling, redness, itching or rash where the needle went in
• Inflammation in organs

Ask your doctors and nurses which signs to watch for and what to do if problems start.⁷ Then tell your team about any new changes, even small ones.

Sources

1. Immunotherapy for Cancer, National Cancer Institute
2. What Is Immunotherapy?, American Cancer Society
3. Immune Checkpoint Inhibitors, National Cancer Institute
4. Monoclonal Antibodies, National Cancer Institute
5. Cancer Treatment Vaccines, National Cancer Institute
6. CAR T-cell Therapy and Its Side Effects, American Cancer Society
7. Side Effects of Immunotherapy, National Cancer Institute
8. Biomarker Testing for Cancer Treatment, National Cancer Institute

For education only, not medical advice. Always talk with your care team about your treatment.