Inclusion Criteria: - Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1 - Postmenopausal women with locally advanced breast cancer or Metastatic Breast Cancer (MBC) whose disease is resistant to Aromatase Inhibitor (AI) therapy - Patients must have measurable disease by RECIST v1.1 or non-measurable disease - Adequate hematologic and end-organ function Exclusion Criteria: - Prior treatment with fulvestrant, PI3K inhibitor, or mTOR inhibitor for advanced breast cancer or MBC - History of clinically significant cardiac or pulmonary dysfunction - History of malabsorption syndrome or other condition that would interfere with enteral absorption - Clinically significant history of liver disease - Active autoimmune disease or active inflammatory disease - Immunocompromised status - Need for current chronic corticosteroid therapy - Pregnancy, lactation, or breastfeeding - Current severe, uncontrolled systemic disease - Known untreated or active central nervous system (CNS) metastases Other protocol-defined inclusion/exclusion criteria may apply.