We tend to think of the immune system as the body’s defense against invaders such as bacteria and viruses. But scientists and physicians now recognize that the immune system can play a vital role in thwarting the growth of cancers as well.

The immune system is complex. It’s made up of cells that work together to protect you from disease. We call these cells “white blood cells.” With the help of proteins called antibodies, white blood cells identify unusual cells or germs and eradicate them from your body. Cancer cells develop and multiply because white blood cells are often unable to recognize and kill them.

Immunotherapies are treatments that help the immune system fight cancer. Stem cell transplants and CAR T-cell therapy are forms of immunotherapy that replace or genetically modify the immune system. However, there are also other techniques, such as medications and vaccines, that allow a patient’s immune system to better detect and eliminate cancerous cells.

Immunotherapy is an exciting new frontier in cancer care, and Washington University Physicians and scientists at Siteman Cancer Center are leaders in immunotherapy research and innovation. They study the immune system in the laboratory, looking for weak points that could be enhanced with new medications or tactics. They also run large clinical trials that bring the latest immunotherapies directly to patients.

What are the different types of immunotherapy?

Washington University Physicians at Siteman Cancer Center have many options to choose from when they decide to treat a patient with immunotherapy. Some immunotherapies are given to the patient as medications; other immunotherapies are vaccines created from the patient’s own tumor tissue. Though immunotherapies may come in different forms, their basic function is the same: to allow the body to identify and kill cancer cells.

Monoclonal antibodies

To guard against invading germs or abnormal cells, the immune system deploys proteins called antibodies. Antibodies bind to antigens, which are molecules on the surfaces of malignant cells and germs. When an antibody attaches to an antigen, the immune system kicks into action, and the body fights the infection or disease.

The immune system tailors antibodies to specific antigens. An antibody for the flu virus, for instance, cannot attach to an antigen on a streptococcus bacterium, which causes the common illness strep throat.

Unfortunately, the body often doesn’t produce antibodies that can attach to the antigens on cancer cells. This means that cancer cells can escape notice and grow and multiply unchecked.

To correct this blind spot in the immune system, scientists have created monoclonal antibodies, or antibodies that match cancer antigens. These antibodies alert the immune system to the cancer.

Monoclonal antibodies are usually administered to patients through an IV or injections.

Bi-specific T-cell engagers (BiTE therapy)

Bi-specific T-cell engagers, or BiTEs, are a form of monoclonal antibody. They work by building links between cancer cells and a form of white blood cells called T-cells, effectively trapping the cancer cells so they can be destroyed more easily.  

Checkpoint inhibitors

Some cancer cells are able to shut down the immune system by triggering molecules on the white blood cells called checkpoints. Checkpoints prevent white blood cells from attacking abnormal cells.

Checkpoint inhibitors are medications that turn off the checkpoints, enabling the white blood cells to pursue cancer cells. They are a form of monoclonal antibody.

Patients typically receive checkpoint inhibitors through an IV infusion.


Vaccines can train the immune system to target cancer cells, just as they train it to attack invading viruses, such as the flu.

It’s important to keep in mind that these vaccines are typically used to help treat existing cases of cancer, not to prevent cancer in healthy patients. However, certain viruses, including the human papilloma virus and hepatitis B, are known to cause various types of cancer. Getting vaccinated against these viruses can substantially lower your risk of developing the cancers they cause.

There are several different methods of preparing cancer vaccines, but the general idea is to introduce a patient’s immune system to his or her cancer in a targeted way so as to provoke an immune response.  This could mean injecting the patient with a dose of antigens collected from his or her tumor tissue. Another technique, known as the dendritic approach, involves collecting dendritic cells from the patient’s immune system, exposing those cells to their tumor tissue in a laboratory, and then injecting them back into the patient.

Most patients treated with cancer vaccines at Siteman receive them in clinical trials. Washington University Physicians and researchers are examining the use of vaccines in a wide range of cancers, including melanoma, breast cancer, brain cancer, head and neck cancer, and lymphoma.

Oncolytic virus therapy

This form of immunotherapy employs viruses that have been tailored to attack cancer cells. When one of these viruses is administered to a patient via injection, it destroys cancer cells and stimulates the immune system to eliminate any other cancer cells that remain.

Currently, oncolytic virus therapy is only used in patients with melanoma. Researchers continue to study this technique to see if it could treat other forms of cancer.

What is it like to receive immunotherapy?

Immunotherapies may be given as intravenous medications or injections. The treatment schedule will depend on the drug and your particular condition.

Because immunotherapies are designed to enhance the body’s own natural defenses against disease, patients often find that they are easier to tolerate than other forms of cancer treatment.

Side effects may include:

  • Skin irritation at the site of an injection or IV insertion
  • Flu-like symptoms
  • Mouth sores

Rarely, patients may experience more severe reactions to immunotherapy, including cardiovascular problems. Your physician will discuss the likelihood of any harmful reaction and will work to ensure that your treatment is safe. Be sure to mention any and all concerns with your care team.

Who can receive immunotherapy?

Immunotherapy may be used in the treatment of a wide range of cancers, including melanoma, lung cancer, prostate cancer, and stomach cancer. At this time, immunotherapy is most often administered to patients who have failed to respond to more common forms of treatment, such as chemotherapy and radiation.

However, ongoing clinical trials are exploring the efficacy of immunotherapy as a first-line treatment. This would mean that patients are given immunotherapy before any other treatments.