Immunotherapy

Immunotherapy, sometimes called biological or biologic therapy, is a type of cancer treatment.

Immunotherapy helps the immune system find and attack diseases such as breast cancer.

The immune system

The immune system is your body’s defence system. It protects you from harmful invaders like bacteria, viruses, and other threats.

It’s made up of different parts, including:

• white blood cells
• lymph nodes
• special proteins.

These all work together to find and destroy anything that doesn’t belong in your body. If something harmful is detected, your immune system activates to fight it and keep you healthy.

How immunotherapy works

Sometimes, cancer can trick the immune system and hide from it.

Immunotherapy helps the immune system find and attack the cancer. It can work in a few ways:

• Boosting the immune system: It makes your defence team stronger so it can fight harder.
• Marking cancer cells: It puts a 'flag' on the cancer cells so the immune system can see and destroy them.
• Removing brakes: Your immune system has 'brakes' to stop it attacking healthy parts of your body. Cancer can use these brakes to stay safe. Immunotherapy takes those brakes off so the immune system can attack cancer.

Checkpoint inhibitor drugs

Some breast cancer cells have high levels of proteins such as PD-L1. This enables them to hide from the immune system, so they can grow and spread.

Checkpoint inhibitors block these proteins so that T-cells (a type of white cell and part of the immune system) can recognise and destroy the cancer cells.

Not all breast cancer cells make PD-L1, so checkpoint inhibitors are not effective for all breast cancer subtypes.

Pembrolizumab (Keytruda) is the most common immunotherapy used in breast cancer. It blocks the PD1 receptor on T-cells so the immune system can attack the cancer cells. 

Other immunotherapy drugs are available in Australia are used in other cancer types. These include drugs such as durvalumab (Imfinzi) and tremelimumab (Imjudo).

Clinical trials are still exploring how effective they are in breast cancer. Talk to your medical oncologist or nurse if you have questions about immunotherapy.

Side effects of immunotherapy

Sometimes the immune system can become overactive because of the immunotherapy. This can cause side effects, which can be serious and permanent. Side effects are best managed early, so it's important to tell your doctor, to receive treatment as soon as possible.

It’s important that the immune system does not attack normal (healthy) cells in the body.

Find out ways you can improve side effects of different immunotherapies, which include:

• fatigue (tiredness)
• dry eyes
• loss of appetite or feeling sick (nausea)
• skin rash, itchy skin
• diarrhoea
• joint pain
• headaches
• breathlessness and a dry cough
• changes in weight or body temperature (can be related to effects on the thyroid gland).

Clinical trials

Several clinical trials are studying how effective immunotherapy is in different types of breast cancer. Ask your medical oncologist about clinical trials that may be suitable for you.