T-cell activation against tumors is determined through the complexity of the tumor microenvironment (TME), which is a milieu of tumor cells, stromal cells, suppressive cytokines, regulatory T cells, myeloid-derived suppressor cells, neoantigens, and expressed MHC molecules, as well as the PD-L1 expression of tumor cells and/or immune cells [17]. The gene discussed is CD274; the disease is neoplasm.