Immunotherapy (sometimes called biological therapy) is a treatment that uses a person's immune system to treat certain cancers. The immune system is made up of a complex network of cells, chemicals, tissues and organs, that defends the body from infection. Immunotherapies work by helping the immune system attack cancer cells and slowing the growth and spread of cancer cells.
Immunotherapy can be given in different ways, including:
- orally, as pills (tablets, capsules) or liquid
- intravenously (injected into a vein)
- topically, as a cream to rub onto skin
- intravesically, administered directly into the bladder.
Immunotherapy can be given in a clinic, your doctor’s office, or at a hospital. How often you have treatment will depend on the type of immunotherapy and the type of cancer. Like other treatments, immunotherapies can be given in cycles. This is a period of treatment followed by a period of rest.
Types of immunotherapy
The main types of immunotherapy can be divided into treatments using monoclonal antibodies, nonspecific immunotherapies, and cancer vaccines.
Antibodies are naturally produced by the body when it detects harmful viruses, bacteria and other substances that cause disease. Antibodies fight infection or disease by targeting cells to alter their growth. The immune system is normally able to detect cells in the body that are “foreign”, such as infections and allow normal cells to be left alone. The immune system detects these cells by using “checkpoint” proteins, which allow an immune response to be switched on and off. Cancer cells use these checkpoints to avoid being detected by the immune system. Proteins called monoclonal antibodies, are made in the laboratory and can be designed to target these checkpoints and other targets. They are usually given intravenously.
Monoclonal antibodies (MABs) may be designed to change cancer cells in different ways:
- Antibodies can attach to cancer cells to ‘flag’ your immune system to destroy that cell. These include checkpoint inhibitors such as pembrolizumab and nivolumab.
- Antibodies can slow the growth of cancer cells by blocking parts of the cell that enable them to grow. These include targets to antigens on cancer cells, such as trastuzumab.
- Radioimmunotherapy uses antibodies to deliver radiotherapy to cancer cells without damaging healthy cells. This is done by attaching radioactive molecules to antibodies in a medical laboratory. These kinds of antibodies can also be used to diagnose some cancers by flagging where cancer cells exist in the body.
- The antibody may carry medicine, such as chemotherapy, directly to cancer cells.
Nonspecific immunotherapies refer to the use of cytokines (proteins produced by white blood cells to control immune responses) to help the body’s immune system destroy cancer cells. Nonspecific immunotherapies, such as interleukin-2 and interferons, are typically given in combination with other cancer treatments, such as chemotherapy or radiation therapy.
Types of cytokines that are made in a laboratory to treat cancer include:
- interferons, which can help the immune system to slow the growth of cancer cells
- interleukins, which can increase the production white blood cells and antibodies to fight cancer
- haematopoietic growth factors, which may be used to counteract some side effects of chemotherapy.
Cancer vaccines are medicines that trigger the body’s immune system to detect cancer cells. There are 2 types of cancer vaccines. Preventive (prophylactic) vaccines may prevent cancer cells from developing; they are only useful for cancer known to be caused by infections, such as the HPV (human papillomavirus) vaccine. Treatment (therapeutic) vaccines prompt the immune system to fight existing cancer cells. For example, sipuleucel-T is a cancer vaccine used to treat prostate cancer.
Clinical trials continue into different types of therapeutic vaccines.
Side effects of immunotherapy
Immunotherapy is usually well tolerated. Side effects from treatment can usually be managed, however, some side effects can prevent someone from being able to continue immunotherapy.
Possible side effects of immunotherapy include:
- nausea, vomiting and diarrhoea
- muscle or joint aches
- changes in weight
- low blood pressure
- breathing difficulties
- inflammation of hormone producing glands, e.g. thyroiditis
- inflammation of organs e.g. hepatitis (liver), colitis (intestine), kidneys
- allergic reactions (rarely)
You may also experience skin reactions at the site of injection if immunotherapy is given intravenously. These include:
For more information about immunotherapy and its side effects, talk to a member of your treatment team, or visit Treatment side effects.