A Study of Multiple Immune and Disease Treatment Combinations in Participants With ER+HER2- Breast Cancer That Has Spread

For more information regarding Bristol-Myers Squibb Clinical Trial participation, please visit www.BMSStudyConnect.com Inclusion Criteria: * Histological and cytological confirmation of adenocarcinoma of the breast * Documented HER2 negative and estrogen receptor (ER) positive status of primary or metastatic tumor tissue using the most recently assessed tumor specimen, according to the local laboratory parameters * ER negativity is defined as \< 1% of tumor cells expressing hormonal receptors via IHC analysis * At least one measurable lesion, as per Response Evaluation Criteria in Solid Tumors version 1.1 \[RECIST v1.1\] that can be accurately assessed at baseline and is suitable for repeated assessment by computed tomography (CT) or magnetic resonance imaging (MRI) * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 * Women and Men must agree to follow specific methods of contraception, if applicable, while participating in the trial Exclusion Criteria: * Allergy or hypersensitivity to any study drugs or their excipients * Any other sound medical, psychiatric and/or social reason as determined by the investigator * Active, known, or suspected autoimmune disease or immune-related diseases * History of unstable or deteriorating cardiac disease within the previous 12 months prior to screening * Prior therapy with anti-programmed death 1 (PD-1), anti-programmed death-ligand 1 (PD-L1) or anti-Cytotoxic T Lymphocyte Antigen 4 (CTLA-4) class antibody * Any major surgery within 4 weeks of the first dose of study treatment Other protocol-defined inclusion/exclusion criteria apply