FOXP3 and neoplasm: As PD-L1 expression levels and the ratio of CD8+/FoxP3+ T cells can be used to characterize tumor immunity conditions (28), we performed a fluorescent multiplex immunohistochemistry (mIHC) assay to determine the expression of PD-L1 together with anti-tumor CD8 T cells and immune-suppressive FOXP3 positive Treg cells in PD-L1 humanized 4T1 syngeneic mouse allograft tumors (Figure 8A).