Illustration of the principle of CAR-T cell immunotherapy consisting of modifying some of the patient抯 immune cells, T lymphocytes, so that they directly and specifically recognize the tumor cells and attack them. T lymphocytes are removed and genetically modified (CAR-T cells) so that they will specifically recognize certain diseased cells. CAR-T cells bond with the cancer cells which triggers various activities (the production of cytokines, expansion of lymphocytes etc.) contributing to the destruction of the cancer cells.