The immune system helps the body fight infections and other diseases, including cancer, by detecting and destroying abnormal cells that have become cancerous. Sometimes cancer cells can hide from the immune system so it doesn’t know where to find them, or the natural immune system might not be strong enough to fight the abnormal cell growth.

Immunotherapy in its various forms can either boost the immune system to help it fight the cancer, or make it easier for the immune system to identify cancer cells and destroy them, or slow their growth.

Like other forms of treatment, immunotherapy is given over a period of time, often in cycles depending on each individual case.

There are many different kinds of immunotherapy which work in different ways and that can also be used in combination with other treatments, such as chemotherapy.

• Cancer vaccines – medicines that trigger the body’s immune system to prevent cancer cells from developing or fight existing cancer cells.
• Monoclonal antibodies – also known as therapeutic antibodies, these are immune system proteins designed to attach to specific targets found on cancer cells so that they will be better seen and destroyed by the immune system.
• Checkpoint inhibitors – medicines that help the immune system respond more strongly to a tumour by releasing the “brakes” that keep T cells (a type of white blood cell and part of the immune system) from killing cancer cells.
• CAR T-cell therapy – an emerging type of treatment in which a patient’s T-cells (a type of immune system cell) are made in the laboratory to have specific receptors that bind to their counterpart proteins on cancer cells. This allows the immune cells to attack the cancer cells when they are introduced back into the body.

Cancer cells learn to survive and grow in a hostile environment as they can hide from the immune system and avoid detection by the body’s own self defences. Once the immune system is alerted and activated, other healthy cells may be recognised as different and vulnerable to attack. This is what causes some of the side effects of immunotherapy.

Immunotherapy does not always cause side effects, however the most common side effects include skin reactions at the needle site such as pain, swelling, soreness, redness, itchiness and a rash.

Other side effects might include:

• Fever
• Chills
• Weakness
• Dizziness
• Nausea or vomiting
• Muscle or joint aches
• Fatigue
• Headache
• Trouble breathing
• Low or high blood pressure
• Swelling and weight gain from fluid retention
• Heart palpitations
• Sinus congestion
• Diarrhoea
• Risk of infection.
• Inflammation of lung leading to breathlessness
• Inflammation of liver
• Other adverse inflammation response

Immunotherapies may, on very rare occasions, also cause severe or even fatal allergic reactions.

In recent years, immunotherapy for cancers in children and young adults is evolving with many young people surviving long-term due to the continued advances in treatments. There are also a number of immunotherapy-based clinical trials for a wide-range childhood cancers, we encourage you to speak to your Paediatric Haematologist-Oncologist if you would like to know more about participating in a clinical trial.

For more information about immunotherapy and its side effects, speak to your Paediatric Haematologist-Oncologist.