Interestingly, the expression of these pro-cytotoxic transcripts in tumours is associated with the counter activation of suppressive mechanisms, such as the expression of IDO1, CTLA4, CD274 (PD-L1), PDCD1 (PD-1), and FOXP3.26 In a study27 centred on the TCGA data set, we found that breast cancers can be classified in four classes according to the ICR signature. This evidence concerns the gene PDCD1 and breast carcinoma.