PDCD1 and neoplasm: Chemotherapy and molecularly targeted therapies are now accompanied by other therapeutic agents like immune checkpoint inhibitors (ICIs) selected for the appropriate patient, as humanized monoclonal antibodies that target inhibitory receptors like CTLA-4, PD-1, LAG-3, TIM-3, and PD-L1 expressed on T lymphocytes, antigen-presenting cells, and tumor cells elicit an anti-tumor response by stimulating the immune system [29].