ERBB2 and breast cancer: Drugs targeting programmed death ligand 1 (PD-L1, e.g., atezolizumab and pembrolizumab), the human epidermal growth factor receptor 2 (HER2, e.g., trastuzumab deruxtecan and tucatinib) and polyadenosine diphosphate-ribose polymerase (PARP, olaparib and talazoparib) have within the past few years gained new indications for specific subgroups of patients with breast cancer [2–7].