Immunotherapy could hold the key to eradicating cancer, but what is it and how does it work?
In some medical circles, immunotherapy is heralded as a wonder treatment; a technique that could fight multiple diseases and conditions by leveraging the body’s own immune system.
It is most commonly known in relation to cancer treatment, but it’s also being honed to treat autoimmune problems, allergic responses, and even age-related diseases. Depending on the type of immunotherapy patients are given, it could also be referred to as biological therapy or targeted treatment. Below we explain why immunotherapy has the potential to be so revolutionary.
Cancer and the immune system
The immune system largely does a fantastic job of policing the body against illness and infection, detecting and eliminating cells that might be performing strangely. In most cases, this stops cancers from developing at all. Cancers that do develop, however, can weaken the immune system, or produce signals that stop the system from attacking it altogether.
The broad aim of immunotherapy is to bolster or elicit a response from the body’s immune system, so that it attacks the cancer and destroy tumours.
Different types of immunotherapy
Cancer immunotherapies aren’t always simple to categorise, as they tend to straddle different therapies, often combining a number of aspects of the immune system. It also doesn’t help that the treatments themselves are often referred to in different terms, such as ‘biological therapy’.
Broadly, immunotherapies are described as either active, where immune cells are made to attack tumour cells, or passive, where preexisting anti-tumour responses are enhanced. There are also hybrid therapies that use a combination of both active and passive approaches.
All work on the general principle that cancer cells have molecules (tumour-associated antigens, TAAs) that can be picked up by the immune system. Exactly how this response is used very much depends on the type of cancer, but here are a few key terms and techniques:
Monoclonal antibodies (mAbs)
‘Monoclonal’ essentially means ‘identical clones’. As that name would suggest, monoclonal antibodies are identical, lab-made antibodies of a particular type. Because these antibodies are all clones of the same parent cell, they bind with the same part of the antigen on the tumour cells.
This can elicit a response from the body’s own immune system, making it easier for the cancer to be found and attacked, a process called antibody dependent cell mediated cytotoxicity, ADCC.
Checkpoint inhibitor therapy
Certain cancers can stop the body’s immune system in its tracks, putting out a signal that will stop immune cells from attacking tumours. A class of mAbs called checkpoint inhibitors stop cancers from fooling the immune system in this way.
There’s a great deal of research in this area of immunotherapy, and a number of checkpoint inhibitors have already been approved for use. The first of these was Ipilimumab, which was given the go-ahead in 2011 and targets the CTLA-4 protein receptor to help the body fight melanoma.
Cytokines make up a broad group of proteins that are key in cell signaling. Many are produced by tumour cells, which the cancer uses to reduce an immune response from the body so it can spread.
Interferon and interleukin are types of cytokines already found in the body, but manmade versions of these have been approved for use in treating certain types of cancer.
For more information on how immunotherapy can be used to fight cancer, Cancer Research UK has a number of resources about different types of treatment.