IFNG and neoplasm: Based on this concept, researchers have examined candidate biomarkers such as the PD-L1 level on tumor cells and the frequency of tumor-infiltrating lymphocytes [77, 78], the levels of IFN-γ–related genes in tumor cells [79, 80], the frequency of mutations in tumor cells [56, 71–73], and the diversity of TCRs in tumor antigen–specific T cells [74, 81, 82].