CD274 and neoplasm: Immune-excluded and immune-desert tumors have been termed “cold tumors” and are essentially characterized by poor T-cell infiltration22, reduced expression of MHC class I, PD-L1, and TMB21, and the presence of immune-suppressive cell populations (e.g. tumor-associated macrophages (TAMs) and T-regulatory cells (Tregs) and myeloid-derived suppressor cells (MDSCs)).23