CDK = cyclin-dependent kinase; HR+/HER2− = hormone receptor–positive/human epidermal growth factor receptor 2–negative. aConsider chemotherapy at each step if overt evidence of visceral crisis., bConsider clinical trials at each step., cShould be used with ovarian function suppression in premenopausal women., dConsider in first line for patients who meet inclusion criteria for PALOMA-3 or MONARCH-2., eConsider additional or other endocrine therapies in patients with long duration of response to endocrine therapy., fIf patient has not yet received CDK4/6 inhibitor, consider abemaciclib alone.