PDCD1 and neoplasm: The T-cell-inflamed phenotype is characterized by the morphologic presence of a preexisting T-cell immune cell infiltrate in the tumor that is negatively regulated by PD-1/PD-L1-mediated adaptive resistance [19] and enriched for response to ICIs through reinvigoration of these preexisting effector antitumor T cells [20], although recruitment of novel T cells that enter the tumor and trigger an effector immune response can also occur [21].