How do you select your first-line endocrine therapy to accompany CDK4/6 inhibitor in metastatic HR+ breast cancer?

If this is a denovo metastatic patient, my choice of endocrine therapy backbone will be an aromatase inhibitor. If the patient develops metastatic disease while on an AI, or within 6-12 months after completing or discontinuing an AI, I will consider fulvestrant. If there is evidence of an ESR1 mutat...