For example, the implementation of patient selection prior to programmed cell death 1 (PD-1)/programmed cell death ligand 1 (PD-L1) inhibitors therapy by the combination of biomarkers reflecting tumor immune microenvironment and tumor cell-intrinsic features, such as PD-L1, tumor-infiltrating lymphocyte, tumor mutational burden, mismatch-repair deficiency, and gut microbiota, could enhance the treatment effect of anti-PD-1/anti-PD-L1 therapy in clinical practice.53 This evidence concerns the gene PDCD1 and neoplasm.