ERBB2 and breast cancer: To date, three orally bioavailable CDK4/6 inhibitors, palbociclib (Ibrance, PD0332991), ribociclib (Kisqali, LEE011) and abemaciclib (Verzenio, LY2834219), have received Food and Drug Administration approval for the treatment of patients with HR + /HER2- metastatic BC.