Immune Checkpoint Inhibitors

Over the last 10 to 15 years, immunotherapy has revolutionized the treatment of cancer. Drugs called immune checkpoint inhibitors are the most frequently used type of immunotherapy and have had the largest impact on cancer care.

Many immune checkpoint inhibitors are approved to treat cancer in the United States. Some are approved to treat many types of cancer and different forms of the same cancer, whereas others are only approved to treat one or two cancer types.

Immune checkpoint inhibitors are often used in combination with other therapies, including other immunotherapy drugs, to treat very advanced cancers as well as early-stage cancers.

Overcoming cancer cells’ evasive maneuvers

Our immune system attacks viruses and harmful bacteria because it views them as “foreign.” Cancer cells are different enough from healthy cells that the immune system should recognize them as threats to be eliminated. But cancer cells and tumors have multiple tactics for evading the immune system. One of the most effective: disguising themselves with the help of proteins called immune checkpoints.

Immune checkpoints are important to human health. These proteins sit on the surface of cells, and when immune cells latch on to them, they get an “I’m fine, leave me alone” message and go on their way. During an active immune response to a viral or other threat, checkpoint proteins are like the brakes on a plane that has just touched down, preventing immune cells from careening out of control and attacking healthy cells and tissues.

Cancer cells take advantage of this safety mechanism, pushing checkpoint proteins to their surface and causing any immune cells in their vicinity—those called T cells in particular—to stand down.

Immune checkpoint inhibitors work by blocking the interaction between immune checkpoint proteins on cancer cells and the corresponding receptor proteins on T cells. With this interaction blocked, cancer cells can’t deliver the “leave me alone” message to T cells—removing the brakes and unleashing an immune assault.

How well do immune checkpoint inhibitors work?

Immune checkpoint inhibitors can be extremely effective in some patients. They have helped many people live for years after their diagnosis and cured a small percentage of people. Researchers have identified certain characteristics in tumors that make these drugs more likely to work and work well, including those that contain cancer cells with many immune checkpoint proteins and those that have a lot of genetic mutations.

But immune checkpoint inhibitors don’t work for everybody. Although scientists don’t fully understand why, they have discovered some reasons. For example, some tumors rely on other ways of weakening the immune response, while others don’t have characteristics that can provoke a strong underlying immune response that can then be augmented with immunotherapy drugs.

Are immune checkpoint inhibitors safe?

Immune checkpoint inhibitors have multiple side effects, including those that are caused by the immune system. The most common include joint pain, skin rash, fatigue, and diarrhea, among several others. More serious side effects include inflammation in the lungs and heart, both of which are immune-related. However, these side effects can be effectively treated, included by lowering the dose of the drug, temporarily stopping its use, and/or using steroids.

Side effects can be more frequent and severe when immune checkpoint inhibitors are used in combination with other drugs. When an immune checkpoint inhibitor is used along with another type of treatment, it’s because studies have shown that the combination works better against patients’ cancer than when the immune checkpoint inhibitor is used alone.

Cancer cells take advantage of this safety mechanism, pushing checkpoint proteins to their surface and causing any immune cells in their vicinity—those called T cells in particular—to stand down.

Immune checkpoint inhibitors work by blocking the interaction between immune checkpoint proteins on cancer cells and the corresponding receptor proteins on T cells. With this interaction blocked, cancer cells can’t deliver the “leave me alone” message to T cells—removing the brakes and unleashing an immune assault.

How well do immune checkpoint inhibitors work?

Immune checkpoint inhibitors can be extremely effective in some patients. They have helped many people live for years after their diagnosis and cured a small percentage of people. Researchers have identified certain characteristics in tumors that make these drugs more likely to work and work well, including those that contain cancer cells with many immune checkpoint proteins and those that have a lot of genetic mutations.

But immune checkpoint inhibitors don’t work for everybody. Although scientists don’t fully understand why, they have discovered some reasons. For example, some tumors rely on other ways of weakening the immune response, while others don’t have characteristics that can provoke a strong underlying immune response that can then be augmented with immunotherapy drugs.

Are immune checkpoint inhibitors safe?

Immune checkpoint inhibitors have multiple side effects, including those that are caused by the immune system. The most common include joint pain, skin rash, fatigue, and diarrhea, among several others. More serious side effects include inflammation in the lungs and heart, both of which are immune-related. However, these side effects can be effectively treated, included by lowering the dose of the drug, temporarily stopping its use, and/or using steroids.

Side effects can be more frequent and severe when immune checkpoint inhibitors are used in combination with other drugs. When an immune checkpoint inhibitor is used along with another type of treatment, it’s because studies have shown that the combination works better against patients’ cancer than when the immune checkpoint inhibitor is used alone.