CD274 and neoplasm: PD-L1 is highly expressed by both tumor-infiltrating immune cells and tumor cells in most solid tumors, including TNBC [6,7,8], and the CD274 gene, which encodes PD-L1, is amplified in most cases of TNBC and is associated with poor outcome, highlighting a key role of the PD-L1/PD-1 axis in the suppression of anti-tumor immunity in these tumors [9,10,11].