More recently, there has been a rapid rise in interest in the assessment of PD-L1 expression in breast cancer, especially in aggressive subtypes such as triple negative breast cancer [37,38], where PD-L1 is expressed in up to 20% of cases [12] and may thus potentially serve as a target for PD-1/PD-L1 pathway-directed immunotherapy. This evidence concerns the gene CD274 and triple-negative breast carcinoma.