Subtitles section Play video Print subtitles Immunotherapy is an exciting area of cancer research that is changing the way we think about cancer treatment. Immunotherapy works by using the body's immune system to fight cancer. The immune system is a complex network of organs, tissues, and cells, and the substances they make. One of the purposes of the immune system is to rid the body of germs, such as bacteria, and abnormal cells, such as cancer cells. Immunotherapy uses different ways to boost the immune system to do a better job of killing cancer cells. This video describes three types of immunotherapy that are used to treat cancer : non-specific immune stimulation, T-cell transfer therapy, and immune checkpoint inhibitors. Non-specific immune stimulation is a type of immunotherapy that stimulates a patient's immune response in a general way. In non-specific immune stimulation, drugs or other substances are used to increase the overall immune response, which can help kill cancer cells. For example, some patients who have had surgery to remove bladder cancer may also be treated with a substance called BCG. When BCG is put into the bladder, it can cause a non-specific immune response that kills cancer cells that remain in the bladder after surgery. This may keep the cancer from getting worse or coming back. T-cell transfer therapy is another type of immunotherapy. T cells are a type of immune cell and are powerful weapons the immune system uses to fight cancer. For T-cell transfer therapy, T cells are taken from a patient and changed in the laboratory to make them better able to target the patient's cancer cells and kill them. Millions of copies of these specially changed T cells are then grown in the laboratory and given back to the patient to fight the cancer. Immune checkpoint inhibitors are a third type of immunotherapy. Immune checkpoints on cell surfaces help control an immune response. Usually immune checkpoints keep T cells inactive, that is in an “off” state, until they are needed. This keeps the T cells from harming normal cells. Cancer cells can take advantage of these checkpoints to switch T cells off. This keeps the cancer cells from being killed. Immune checkpoint inhibitors are drugs that block the checkpoints. This frees the T cells to attack the cancer. These three types of immunotherapy are effective ways to treat cancer, but they don't work for every patient and can cause serious side effects. Researchers supported by the National Cancer Institute are working to learn more about how the immune system works to fight cancer. By studying this, researchers can learn how to improve immunotherapy for all patients.