PDCD1 and cancer: Immunotherapy has been proposed as the fourth method of cancer treatment after surgery, chemotherapy, and radiotherapy.25,26 Blockade of the PD-1/PD-L1 pathway using specific monoclonal antibodies is widely accepted as a successful strategy for the normalization of cancer immunotherapy.27,28,29,30,31,32 However, treatments targeting the PD-1/PD-L1 pathway cannot be applied to all patients.