ERBB2 and breast cancer: Indeed, the expression of PD-L1 in HER-2+ BC is associated with increased OS [53] and monoclonal antibodies such as, Atezolizumab, Pembrolizumab, Nivolumab, directed against PD-1 receptor and its ligand PD-L1, are able to restore antitumoral immunity [54,55,56].