The FDA and EMA have approved abemaciclib and ribociclib, cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors, in combination with endocrine therapy (ET) as adjuvant treatment to patients with hormone receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative early breast cancer (EBC) to reduce the risk of recurrence in addition to its use in the treatment of metastatic disease. This evidence concerns the gene CDK4 and breast carcinoma.