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 organs and tissues of the lymph system.
Immunotherapy is a type of biological therapy. Biological therapy is a type of treatment that uses substances made from living organisms to treat 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 or 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 don’t contain them.
Even though the immune system can prevent or slow cancer growth, cancer cells can avoid destruction by the immune system. 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 to the cancer cells.
Immunotherapy helps the immune system to better act against cancer. Several types of immunotherapy are used to treat cancer. These include:
Immune checkpoint inhibitors, which are drugs that block immune checkpoints. These checkpoints are a normal part of the immune system and keep immune responses from being too strong. By blocking them, these drugs allow immune cells to respond more strongly to cancer.
T-cell transfer therapy, which is a treatment that boosts the natural ability of your T cells to fight cancer. In this, immune cells are taken from your tumor. Those that are most active against your cancer are selected or changed in the lab to attack your cancer cells, grown in large batches, and put back into your body through a needle in a vein.
Monoclonal antibodies, which are immune system proteins created in the lab that are designed to bind to specific targets on cancer cells. Some monoclonal antibodies mark cancer cells so that they will be better seen and destroyed by the immune system. Such monoclonal antibodies are a type of immunotherapy.
Treatment vaccines, which work against cancer by boosting your immune system’s response to cancer cells. Treatment vaccines are different from the ones that help prevent disease.
Immune system modulators, which enhance the body’s immune response against cancer. Some of these agents affect specific parts of the immune system, whereas others affect the immune system in a more general way. Immunotherapy drugs have been approved to treat many types of cancer (solid tumors and hematologic malignancies). However, immunotherapy is not yet as widely used as surgery, chemotherapy, or radiation therapy.
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 the body. Different people have different side effects. The ones patients might have and how they make patients feel will depend on how healthy they are before treatment, and the type of cancer, how advanced it is, the type of immunotherapy, and the dose.
Patients might be on immunotherapy for a long time, and side effects can occur at any point during and after treatment. And the most common organs affected by immunotherapy are lungs, colon, skin, glands, kidneys, and liver.
Currently, hundreds of clinical trials are going on to determine the efficacy and safety of immunotherapy in almost all kinds of cancer, and the list of indications for immunotherapy in so many kinds of cancer is rapidly growing.
- The writer is Chief Medical Oncologist and Head of Department of Medical Oncology