Monoclonal antibodies either work to 'take the brakes off' the immune system or they prevent tumour cells from continuing to divide.
Our bodies make proteins called antibodies to fight infection and disease. Monoclonal antibodies are versions of these natural immune system proteins (antibodies), but are made in a laboratory.
As can be seen by the fact that their names end in '–mab', many checkpoint inhibitor drugs are, in fact, monoclonal antibodies.
Other monoclonal antibodies include drugs that target receptors (molecules) on cell surfaces involved in 'signalling pathways' within cells.
Signalling pathways are groups of proteins/molecules that work together to control particular cell functions, such as cell division, cell migration (movement) or cell death. If something goes wrong with a pathway, cells can multiply and spread, leading to the formation and growth of a tumour.
Research is beginning to identify receptors (molecules) which can lead to brain tumour formation when their structure is changed for some reason (mutated) and the signalling pathways they control act abnormally. An example of such a receptor is called EGFR (epidermal growth factor receptor).
Monoclonal antibodies are used to block mutated receptors to stop tumour cells from continuing to divide.