CDK4 and breast cancer: In recent years, adjuvant molecularly targeted therapies with pertuzumab and trastuzumab for human epidermal growth factor 2 (HER‐2)‐positive breast cancer,10, 11 cyclin‐dependent kinases 4 and 6 (CDK4/6) with abemaciclib for hormone receptor (HR)‐positive/HER‐2–negative breast cancer,12 and programmed cell death 1 with pembrolizumab for triple‐negative (TN) breast cancer13 have been developed to prolong invasive disease‐free survival and to decrease morbidity associated with the primary breast cancer.