ERBB2 and breast cancer: Immunotherapy, based on the immune checkpoint inhibitor molecules (ICIs), specific for programmed cell death protein 1 (PD-1), programmed death ligand 1 (PD-L1), and CTLA-4, which are either administered as a single agent or in combination with either a humanized monoclonal antibody, such as trastuzumab, in HER2+ BC settings, or any other chemotherapeutic drug in the TNBC scenario, have been the recent candidates in clinical trials (8).