Since trastuzumab has been demonstrated to show promising antitumor activity for HER2-positive breast cancer patients, trastuzumab alone, or in combination with other cytotoxic drugs, has been widely used in clinical practice to treat patients with that disease and most of the outcomes resulted in longer OS and PFS and higher ORR,17–20 even though that therapeutic approach is associated with a risk for cardiotoxicity.21,22 Trastuzumab-based adjuvant therapy has become the standard of care for HER2-positive breast cancer patients. Here, ERBB2 is linked to breast cancer.