EMBER-3

Main inclusion criteria:

• Have a diagnosis of ER+, HER2- locally advanced or metastatic breast cancer
• Have disease that has demonstrated progression on or after an aromatase inhibitor alone or in combination with a cyclin-dependent kinase (CDK)4/6 inhibitor – Participants are expected to have received prior treatment with a CDK4/6 inhibitor, if this treatment is approved and can be reimbursed
• Must be deemed appropriate for treatment with endocrine therapy
• If female, have a postmenopausal status by natural or surgical means or by ovarian function suppression
• Have RECIST evaluable disease (measurable disease and/or nonmeasurable bone-only disease)

Main exclusion criteria:

• Have received prior treatment with chemotherapy (except for neoadjuvant/ adjuvant chemotherapy), fulvestrant, or any investigational-ER-directed therapy (including SERDs and non-SERDs), any PI3K-, mTOR- or AKT- inhibitor
• Have visceral crisis, lymphangitic spread within the lung, or any evidence of leptomeningeal disease.
• Have symptomatic or untreated brain metastasis.