The development and endorsement of CDK4/6 inhibitors like palbociclib, ribociclib, and abemaciclib represent a vital advancement in ER+ breast cancer treatment. These drugs specifically target CDK4 and CDK6, crucial regulators of the cell cycle. They have demonstrated substantial efficacy in impeding metastasis for individuals with metastatic ER+ breast cancer, and are now also being used in the adjuvant setting. The gene discussed is CDK4; the disease is breast cancer.