CD274 and neoplasm: In addition to tumor-derived factors, such as exosomes and cytokines, macrophages themselves, the hypoxic TME environment, lactic acid accumulation, cytokines originating from various immune cells in the TME, as well as the conditions caused by tumor therapy, such as chemotherapy, radiotherapy, and CAR-T cell immunotherapy, have a great influence on the expression of PD-L1 on TAM [76].