Taken together, our analysis suggest that genomic instability and the consequent increased in mutation burden in breast cancers mediated by BRCA1- and BRCA2-deficiency may not be the sole determinant of PD-L1 and PD-1 expression, immune infiltrates, and T cell-inflamed signature, and therefore may be insufficient to predict clinical benefit from immunotherapy. This evidence concerns the gene BRCA2 and breast cancer.