Nowadays, several biological therapies entered the clinic, including the monoclonal antibodies (mAb) trastuzumab, pertuzumab, the tyrosine kinase inhibitor (TKI) neratinib, and the antibody drug conjugate (ADC) T-DM1 and are now available for the (neo)adjuvant treatment of HER2-positive early BC [[4], [5], [6]]. The gene discussed is ERBB2; the disease is breast cancer.