Immunotherapy is treatment that uses certain parts of a person’s immune system to fight diseases such as cancer. Different types of immunotherapy drugs are available, and they work in different ways.
Immunotherapy can work by stimulating the immune system to find cancer cells or by adding components to a person’s immune system such as man-made immune system proteins.
Clinical trials are underway in triple negative breast cancer and HER2-positive breast cancer to test the effectiveness of immunotherapy drugs.
Our immune system is made up of white blood cells, lymph glands and organs, such as the spleen, that protect us from disease.
Two main types of white blood cells (called lymphocytes) are in the immune system:
The immune system usually prevents cancer from developing by detecting and destroying abnormal cell growth. Sometimes the body’s immune system is not strong enough to stop cancer from developing.
Immunotherapy, sometimes called biological or biologic therapy, is a type of cancer treatment that works by boosting the person’s immune system to fight diseases such as cancer. Immunotherapy typically works on specific proteins involved in the immune system to enhance the immune response.
Types of immunotherapies include:
How does immunotherapy work in breast cancer?
An important part of the immune system is its ability to keep itself from attacking normal cells in the body. To do this, it uses proteins (or "checkpoints") on immune cells (T cells) that need to be turned on (or off) to start an immune response. Breast cancer cells sometimes use these checkpoints to avoid being attacked by the immune system.
There are drugs that block different checkpoint proteins, including:
PD-1 and CTLA-4 are found on T cells, and PD-L1 is found on cancer cells.
PD-1 helps to prevent T cells from attacking other cells in the body (like an “off” switch) by binding to PD-L1, a protein on some normal (and cancer) cells. Some cancer cells have high levels of PD-L1, which helps them hide from the immune system.
CTLA-4 is another checkpoint protein on some T cells that acts as a type of “off” switch to help keep the immune system in check.
Checkpoint inhibitors are drugs designed to block these checkpoint proteins to enable the T cells to recognise and destroy cancer cells. Checkpoint inhibitors are a type of immunotherapy being studied in clinical trials for the treatment of breast cancer.
Some breast cancer cells use certain proteins, called immune checkpoint proteins, such as PD-L1, to hide from the immune system, enabling them to grow and spread. Immune checkpoint inhibitors target these immune checkpoint proteins and help remove barriers that stop the immune system from finding and attacking these breast cancer cells. However, some breast cancer cells do not make PD-L1, and this means that immune checkpoint inhibitors cannot be used for everyone.
Keytruda is a drug that targets PD-1, a protein on T cells that normally helps keep them from attacking other cells in the body. By blocking PD-1, this drug boosts the immune response against breast cancer cells. Keytruda is available on the PBS for triple negative metastatic breast cancer.
Clinical trials are underway for other immune checkpoint inhibitors for triple negative breast cancer and HER2-positive breast cancer.
Side effects of immunotherapies may include:
Some of the side effects, such as diarrhoea, can be serious. It is important to tell your doctor or nurse if you have any side effects with immunotherapy so that you can receive treatment as soon as possible.
Current clinical trials are studying the effectiveness of immunotherapy as a treatment for breast cancer. Talk to your medical oncologist about clinical trials that may be suitable for you. Read about clinical trials and breast cancer.
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*This article does not provide medical advice and is intended for informational purposes only.
Please consult a medical professional or healthcare provider if you're seeking medical advice, diagnoses, or treatment.