These include the fine-tuning of crucial immune checkpoint pathways like PD-1/PD-L1, the induction of T cell exhaustion and promotion of regulatory T cell suppression, the profound remodeling of the tumor microenvironment via metabolic reprogramming and myeloid cell manipulation, and the direct influence on intrinsic tumor cell properties such as epigenetic states and cancer stem cell characteristics. This evidence concerns the gene PDCD1 and neoplasm.