Alpelisib plus fulvestrant (classified as an estrogen receptor antagonist) have synergistic antitumor activity and are used in patients with PIK3CA-mutated, HR positive, HER2-negative advanced breast cancer who had received endocrine therapy previously as cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors (3). This evidence concerns the gene CDK4 and breast cancer.