Abstract

In the tumour microenvironment, several immunomodulatory molecules are expressed by cells of the immune system as well as by tumour cells. Molecules that inhibit anti-tumour immune responses include cytokines, several growth factors, enzymes and ligands that bound to specific inhibitory molecules on immune cells (immune checkpoints CTLA-4, PD-1). Immune checkpoint inhibitors block inhibitory signals prevalent in the tumour microenvironment and thereby force the immune system to attack malignant cells. Currently, three immune checkpoint inhibitors (ipilimumab- antibody against CTLA-4, pembrolizumab and nivolumab- antibodies against PD-1) have reached everyday practice to treat melanoma, non-small cell lung cancer and renal cancer. Moreover, in the near future, lengthening of the list of these drugs is eagerly awaited. Immune checkpoint therapy is a new effective anti-cancer therapy which has expanded treatment options in a number of aggressive solid tumours.