Palbociclib and Ribociclib, which are cyclin-dependent kinase inhibitors (CDKIs), have been approved for the first-line treatment of hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2−) metastatic breast cancer patients [12], as they have both demonstrated that they significantly prolong median progression-free survival (PFS) in advanced breast cancer patients, when combined with aromatase inhibitors [13]. This evidence concerns the gene ERBB2 and breast carcinoma.