ERBB2 and breast cancer: Trastuzumab, an antibody targeting human epidermal growth factor receptor 2 (HER2), delivered with chemotherapy for patients with HER2-positive breast cancer has made a great progress in the therapy of metastatic and adjuvant settings (Piccart-Gebhart et al., 2005; Romond et al., 2005; Perez et al., 2014; Cameron et al., 2017).