What Is Immunotherapy?

The simple version

Immunotherapy is a type of cancer treatment that helps your immune system fight cancer. The immune system helps your body fight infections and other diseases. It is made up of white blood cells and the organs and tissues of the lymph system.

Immunotherapy is a type of biological therapy — a treatment that uses substances made from living organisms to treat cancer.

Immunotherapy helps your own immune system act against cancer.

How it works against cancer

As part of its normal function, the immune system detects and destroys abnormal cells and most likely prevents or curbs the growth of many cancers. For instance, immune cells are sometimes found in and around tumors. These cells, called tumor-infiltrating lymphocytes (TILs), are a sign that the immune system is responding to the tumor. People whose tumors contain TILs often do better than people whose tumors do not.

Even though the immune system can prevent or slow cancer growth, cancer cells have ways to avoid destruction. For example, cancer cells may:

• have genetic changes that make them less visible to the immune system
• have proteins on their surface that turn off immune cells
• change the normal cells around the tumor so they interfere with how the immune system responds

Immunotherapy helps the immune system to better act against cancer.

The types of immunotherapy

Several types of immunotherapy are used to treat cancer:

• Immune checkpoint inhibitors are drugs that block immune checkpoints. These checkpoints are a normal part of the immune system that keep immune responses from being too strong. Blocking them allows immune cells to respond more strongly to cancer.
• T-cell transfer therapy boosts the natural ability of your T cells to fight cancer. Immune cells are taken from your tumor, the most active ones are selected or changed in the lab, grown in large batches, and put back into your body through a needle in a vein. It may also be called adoptive cell therapy.
• Monoclonal antibodies are immune system proteins created in the lab, designed to bind to specific targets on cancer cells. Some mark cancer cells so the immune system can better find and destroy them.
• Treatment vaccines work against cancer by boosting your immune system's response to cancer cells. They are different from vaccines that help prevent disease.
• Immune system modulators enhance the body's immune response against cancer. Some affect specific parts of the immune system, while others affect it more generally.

Which cancers it treats

Immunotherapy drugs have been approved to treat many types of cancer. However, immunotherapy is not yet as widely used as surgery, chemotherapy, or radiation therapy. To learn whether immunotherapy may be used for a specific cancer, the National Cancer Institute provides adult and childhood cancer treatment summaries.

Side effects

Immunotherapy can cause side effects, many of which happen when the immune system that has been revved up to act against the cancer also acts against healthy cells and tissues in your body.

Side effects can happen when the boosted immune system affects healthy cells too.

What to expect

How it is given. Immunotherapy may be given into a vein (IV), as pills or capsules you swallow (oral), as a cream you rub on your skin (topical, which can be used for very early skin cancer), or directly into the bladder (intravesical).

Where you go. You may receive immunotherapy in a doctor's office, clinic, or outpatient unit in a hospital. Outpatient means you do not spend the night in the hospital.

How often. How often and how long you receive immunotherapy depends on your type of cancer and how advanced it is, the type of immunotherapy, and how your body reacts. You may have treatment every day, week, or month. Some types are given in cycles — a period of treatment followed by a period of rest that gives your body a chance to recover and respond.

How you will know if it is working. You will see your doctor often for physical exams and to be asked how you feel. You will have medical tests, such as blood tests and different types of scans, which measure the size of your tumor and look for changes in your blood work.

Current research

Researchers are focusing on several areas to improve immunotherapy, including finding solutions for resistance (so the treatment keeps working), finding ways to predict who will respond, learning more about how cancer cells evade the immune system, and reducing side effects. Clinical trials are testing immunotherapy across the United States and Canada.