We investigated the effect of breast cancer cells on the expression level of ICs on Tregs (defined as CD4+CD25+FoxP3+Helios+), in addition to the effect of anti-PD-1, anti-PD-L1 or both mAbs on the expression of ICs on Tregs in the presence of breast cancer cells (Figure 6A). This evidence concerns the gene PDCD1 and breast cancer.