In recent years, cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i), including palbociclib, ribociclib, and abemaciclib, have been approved for the treatment of hormone receptor-positive (HR+), human epidermal growth factor receptor-negative (HER2-) advanced breast cancer (ABC)[1]. The gene discussed is ERBB2; the disease is breast carcinoma.