CLINICAL TRIAL / NCT04975308

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) - Have a performance status of 0 or 1 on the Eastern Cooperative Oncology Group scale (Oken et al. 1982) - Have adequate renal, hematologic, and hepatic organ function - Must be able to swallow capsules/tablets 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. - Have serious preexisting medical conditions that, in the judgment of the investigator, would preclude participation in this study - Known allergic reaction against any of the components of the study treatment