ERBB2 and breast cancer: Palbociclib (PD033291), abemaciclib (LY2835219), and ribociclib (LEE011) are approved for the treatment of hormone‐sensitive and HER2‐negative advanced breast cancer patients, where they have been shown to improve progression‐free survival in largely metastasized breast cancer patient cohorts (Finn et al, 2016; Goetz et al, 2017).