CD274 and neoplasm: In the context of biomarker analysis, PD-L1 expression in TCs, that in tumor infiltrating immune cells (TIICs), and a high level of CD8+ T cell infiltration have been shown, in several clinical trials testing anti-PD-1 and anti-PD-L1 antibody therapy, to be potential predictive biomarkers of clinical efficacy [17–20].