The emergence of CDK4/6 inhibitor (CDK4/6i) is offering clinical advances, providing promising therapeutic outcomes in certain breast cancer, such as palbociclib hydrochloride (PAL)3 in ER+/HER2− breast cancer and ribociclib and abemaciclib in HR+/HER2− breast cancer4,5. The gene discussed is CDK4; the disease is breast cancer.