CD274 and cancer: This immunosuppressive milieu is orchestrated by key cellular components, including M2-polarized tumor-associated macrophages (TAMs), regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSCs), PD-L1-expressing tumor cells, and pro-fibrotic cancer-associated fibroblasts (CAFs), which collectively inhibit effector T cell function and promote immune exclusion/desert phenotypes.