How Immune Checkpoint Inhibitors Treat Cancer

Medically Reviewed by Laura J. Martin, MD on June 14, 2020

Immune checkpoint inhibitors are medicines that help your body fight cancer. They take the brakes off the immune system -- your body's defense against germs -- so it can attack cancer cells at full force.

They're a kind of immunotherapy, a treatment that uses your immune system. You may also hear your doctor call it "checkpoint blockade immunotherapy."

How Do Immune Checkpoint Inhibitors Work?

To stay healthy, your immune system finds and destroys invaders, such as viruses and bacteria. To tell the difference between these dangerous cells and healthy ones, it uses proteins called checkpoints.

These proteins live on the surface of immune cells called T cells. Some checkpoints tell the T cells to "turn on" their immune response and attack. Others send a signal that tells them to "switch off," so they won't accidentally harm healthy cells.

But cancer cells are tricky. Some make proteins that bind to those checkpoints, which causes them to send an "off" signal. This keeps your immune system from activating and killing those cancer cells.

Immune checkpoint inhibitors attach to these checkpoints. They block cancer cells from hitting the off switch. This allows T cells to find and destroy cancer cells.

What Types of Cancer Do They Treat?

Your doctor may suggest an immune checkpoint inhibitor based on your overall health and the kind of cancer you have. Other things that affect the decision to try this treatment are the stage of your cancer and if you've already had certain treatments.

Immune checkpoint inhibitors don't work for all kinds of cancer. You may need to get a test to see if your cancer cells have large amounts of certain checkpoint proteins.

The FDA has approved immune checkpoint inhibitors to treat some people with these cancers:

Scientists are also studying immune checkpoint inhibitors on other types of cancer in studies called "clinical trials." If you're interested in joining one, ask your doctor if it's a good idea for you.

How Do You Get Immune Checkpoint Inhibitors?

Your doctor puts this treatment into a vein in your arm or chest. The medicine drip usually takes about a half-hour to an hour for each session.

How many treatments you'll need depends on your cancer and the type of drug. You may get them every 1 or 3 weeks for a few months. Or you may need treatment for a year or more.

Immune checkpoint inhibitors are usually less harsh on your body than chemotherapy. You don't need any special preparation before treatment.

What Are the Side Effects?

Each type of checkpoint inhibitor has its own set of side effects, but the most common ones are:

The treatment can lead to inflammation, which may cause problems like:

If you have any side effects, talk to your doctor. Medicines, such as corticosteroids, can help keep them under control. For more severe symptoms, you may need to stop your immune checkpoint inhibitor treatment until your body recovers.

WebMD Medical Reference



American Cancer Society: "Immune Checkpoint Inhibitors and Their Side Effects," "Monoclonal Antibodies and Their Side Effects."

Cancer Research UK: "Checkpoint Inhibitors."

European Society for Medical Oncology: "Immunotherapy Side Effects."

MD Anderson Cancer Center: "Immune Checkpoint Inhibitors."

Memorial Sloan Kettering Cancer Center: "Checkpoint Inhibitors."

Moffitt Cancer Center: "Checkpoint Blockade Immunotherapy."

National Cancer Institute: "Immune Checkpoint Inhibitors."

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