CDK4 and breast cancer: Recently, a phase 3, randomized, double-blind trial included a study population of pre-, peri-, and post-menopausal women and men with hormone receptor-positive, human epidermal growth factor receptor 2–negative advanced breast cancer who had had a relapse or disease progression during or after treatment with an aromatase inhibitor, with or without previous cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor therapy.