Depending on the molecular subtype, the treatment options for metastatic breast cancer are largely focused on: endocrine therapy for patients with human epidermal growth factor receptor 2 (HER2)-negative luminal metastatic tumors; anti-HER2 therapy for patients with HER2-positive metastatic tumors; systemic chemotherapies, in triple negative breast cancer or in highly symptomatic patients [4]. Here, ERBB2 is linked to metastatic neoplasm.