CD274 and neoplasm: In addition to the inhibition of the immune microenvironment of tumor cells represented by PD-L1, the exhausted state of T cells indicated by PD-1, LAG-3, and Tim-3, the activation state of T cells marked by CD8 and CD28, and the T cell killing function effectuated by INF-γ, granzyme B, and perforin also provide a vital and predictive effect on the efficacy of immunotherapy.