Hormone receptor positive (ER+/PR+) metastatic BC is typically treated with hormone therapy (tamoxifen/aromatase inhibitor), and an amalgamation of hormone therapy with targeted drugs such as a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor, everolimus, and phosphoinositide 3-kinase (PI3K) inhibitor is shown to improve the effectiveness of monotherapy. The gene discussed is CDK4; the disease is breast cancer.