PDCD1 and cancer: This revolution in cancer therapy took place in a very short time and currently, several years after the start of research, monoclonal antibodies such as anti-cytotoxic T cell antigen 4 (anti-CTLA-4), anti-programmed cell death protein 1 (anti-PD-1) and anti-programmed cell death protein ligand 1 (anti-PD-L1) are used in routine treatment or are undergoing the last stages of clinical trials in patients with various types of cancer [2].