Results from phase III trials have favored the combination of AIs with mTOR inhibitor, everolimus, and CDK 4/6 inhibitors (abemaciclib, palbociclib, and ribociclib), by providing superior efficacy in patients who have previously received an AI38, 59 and thus have been approved for metastatic HR + BC.47, 60, 61, 62. This evidence concerns the gene MTOR and breast cancer.