Dr Tamás Martin
Medical Oncologist
Immunotherapy uses your body’s own immune system to fight cancer. It’s not a single medication, but a category of therapies that can treat certain types of cancer, often alongside other treatments.
Here’s a look at the main types of immunotherapy treatments and how they work, what cancer types they work on, and how immunotherapy compares to chemotherapy.
Immunotherapy is a category of medications that train your immune system to recognise and kill cancer cells.
The immune system is the body’s defence force. It’s a network of white blood cells, tissues, and organs that constantly hunt down bacteria, infections, and other foreign invaders before they can make you sick.
Cancer cells are tricky invaders that can outsmart your immune system. Even when it spots them, they can grow faster than your immune cells can respond. Cancer cells can also hide or produce signals that stop immune cells from attacking them.
Immunotherapy drugs help train your immune system to identify hidden cancer cells and mark them for destruction. Some drugs can help you produce more cancer-fighting immune cells, giving you a stronger defence over time (1,2,3,4).
Immunotherapy treatments travel through your bloodstream and help your immune system target cancer cells throughout your body. Depending on the drug, it may work by (1,2,3,4):
Immunotherapy might not cure cancer, but it can often slow tumour growth and control the disease. Sometimes, it leads to remission, meaning while it’s not cured, there are no active signs of cancer.
Immunotherapies work on various parts of the immune system, and researchers are developing new ones all the time. The most common types in use today include checkpoint inhibitors, monoclonal antibodies, therapeutic cancer vaccines, and CAR T-cell therapy.
Checkpoint inhibitors, (also called immune checkpoint inhibitors) block proteins that act like “off switches” for your immune system (4). These checkpoint proteins normally sit on the surface of T cells, immune cells that hunt down harmful cells. Checkpoint proteins control T cell activity and put the brakes on when needed, preventing them from becoming too aggressive and attacking healthy cells. However, cancer cells can hijack these switches, tricking your T cells into standing down instead of attacking.
Checkpoint inhibitor drugs prevent T cells from hitting the brakes when they encounter cancer cells, allowing your immune cells to do their job, recognising and killing cancer cells. There are several types of checkpoint inhibitor drugs, including PD-1, CTLA-4, and LAG-3 inhibitors. Each targets a specific checkpoint protein (4).
One of the ways the immune system helps keep you healthy is by making antibodies, proteins that attach to specific antigens, or targets on harmful cells and remove them from your body. Monoclonal antibodies are made in a lab and designed to mimic this natural process, targeting antigens found on cancer cells.
Monoclonal antibodies can act as both immunotherapy and targeted therapy. They help your immune system find and attack cancer cells more effectively, while also attaching to specific targets that are more common on cancer cells, helping treatment focus its effects while potentially reducing damage to healthy tissues (4).
Monoclonal antibodies work by (4):
Unlike vaccines that prevent cancer, like the HPV vaccine, cancer treatment vaccines help your body fight cancer you already have. The vaccines target antigens found on cancer cells, and help your body remember them long after treatment ends.
They may (2):
Cancer vaccine immunotherapies are commonly used to treat early-stage bladder cancer, and some forms of melanoma. Many more vaccines are in development.
CAR T-cell therapy is a personalised treatment made from white blood cells taken from your body. Doctors remove T cells from your blood, add a lab-made protein that helps T cells find and kill cancer cells, called chimeric antigen receptor (CAR), to their surface, and grow millions of copies in a lab. These modified CAR T-cells are then infused back into your bloodstream, where they travel through your body to hunt down cancer cells (4).
It’s commonly used to treat leukaemia and lymphoma, and doctors are studying its use in other cancers.
Immunotherapy doesn’t work on every cancer, but it might help some types of (3):
To determine whether you’re a candidate, your care team will also weigh:
Your cancer care team will test your cancer, assess your health, and determine whether immunotherapy is a good option and which treatment might work best.
Immunotherapy has produced long-lasting remissions for many people with certain types of advanced cancer. However, not every cancer responds to the treatments in the same way. Sometimes, the drugs don’t work as well as expected, or they can stop working after a period of time.
Because every person’s cancer is different, it’s hard to predict how well immunotherapy will work for you.
Possible benefits include (1,2,3,4):
Depending on the drug, immunotherapy may also cause side effects, which can range from mild, like a skin rash or fatigue, to more severe problems that affect your immune system or organs.
Your cancer specialist can give you the most accurate information about what you might expect from immunotherapy treatment.
Immunotherapy and chemotherapy work in very different ways, with different side effects and results (4).
| Treatment | Chemotherapy | Immunotherapy |
|---|---|---|
| How it Works | Kills all fast-growing cells, including cancer cells and healthy cells, such as hair cells and those lining your GI tract. | Boosts your immune system so it can find and kill only cancer cells. |
| Side Effects | Hair loss, fatigue, nausea, vomiting, diarrhoea, and a compromised immune system are common. These start early, but typically fade after treatment ends. | Can cause flu-like symptoms, fatigue, rashes or inflammation in healthy organs. Side effects may appear later and last longer after treatment ends. |
| Results | Shrinks tumours faster. Can be used for most cancer types and stages, though cancer can recur if cells are missed. | May take longer to work, but the benefits can last longer by training your immune cells to fight current or future cancer cells. |
Depending on your cancer type, biomarkers, and stage, your oncologist may use both treatments together or one after the other to achieve the best results.
Immunotherapy offers a promising way to treat cancer. Research continues to expand the role of immunotherapy, with new approaches being developed to improve effectiveness and safety. Talk to your cancer specialists to see if these treatments could be a good option for you.
References:
This information is provided for educational purposes only. It is general in nature and is not intended to replace professional medical advice, diagnosis, or treatment. Always consult your healthcare team regarding any questions or concerns about your health or care.
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