PDCD1 and breast cancer: Although we could not exclude that the low PD-L1 staining in TILs was not linked to technical difficulties in maintaining good immunoreactivity of embedded tissues once sectioned [70], our findings confirmed previous data on luminal BC patients [71, 72] that showed low PD-1 and PD-L1 expression in luminal BC and were not in favor of anti-PD-1 or PD-L1 use in luminal BC type.