CD274 and neoplasm: Researches have shown that PD-L1 was expressed on the cell surface of both disseminated tumor cells and immune cells in MPE/MA,18,21,37 and the expression could be further up-regulated by chemotherapy and PD-1 inhibitor treatment.21,38,39 In this study, we further confirmed that PD-L1 was broadly expressed on freshly-isolated cells of patient-derived MPE/MA, including tumor cells, MDSCs, macrophages and T cells.