Immunotherapies work by stimulating your immune cells, or T-cells, to attack tumor cells. Your T-cells can be activated by injecting drugs or antibodies into your system, or your T-cells may be collected from your blood and reprogrammed to fight cancer cells in a laboratory. They are then re-injected into your system.
They then go to work attacking certain proteins found in cancer cells but not in normal cells. Because it doesn’t hurt normal cells, immunotherapy generally has few side effects.