STRIDE - STimulating Immune Response In aDvanced brEast Cancer

Inclusion Criteria: * Postmenopausal women as defined in the protocol * Estrogen receptor (ER)-positive and/or progesterone receptor (PgR)-positive, histologically or cytologically confirmed primary carcinoma of the breast * Expressing at least one of the following five human leukocyte antigen (HLA) haplotypes, as centrally assessed by HLA genotyping from whole blood: HLA-A2, -A3, -A11, -B7, or -B35 * Locally advanced, recurrent, or metastatic breast cancer (Subject must have at least one lesion not located in bone) * Measurable disease by Response Evaluation Criteria in Solid Tumors (RECIST), and inoperable * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 * Adequate hematologic, hepatic, and renal function within two weeks prior to initiation of therapy, as defined by the protocol * Other protocol-defined inclusion criteria may apply Exclusion Criteria: Disease Status * PD either during hormonal therapy for early breast cancer (adjuvant therapy) or within 48 months from the initiation of such therapy * Human epidermal growth factor receptor 2-positive (HER2+) breast cancer as defined in the protocol * Autoimmune disease that in the opinion of the investigator could compromise the safety of the subject in this study (Exception will be granted for well-controlled Type I diabetes mellitus) * Recognized immunodeficiency disease, including cellular immunodeficiencies, hypogammaglobulinemia or dysgammaglobulinemia; hereditary or congenital immunodeficiencies * Past or current history of malignant neoplasm other than breast cancer (BRCA), except for curatively treated non-melanoma skin cancer, in situ carcinoma of the cervix, or other cancer curatively treated and with no evidence of disease for at least five years * Known active Hepatitis B infection or carrier state and/or Hepatitis C infection, known Human Immunodeficiency Virus infection, or any other infectious process that in the opinion of the investigator could compromise the subject's ability to mount an immune response or could expose her to the likelihood of more and/or severe side effects Pre-therapies * Receipt of immunotherapy (for example \[e.g.\], interferons; tumor necrosis factor; interleukins; growth factors granulocyte macrophage-colony stimulating factor \[GM-CSF\], granulocyte-colony stimulating factor \[G-CSF\], macrophage-colony stimulating factor \[M-CSF\], or monoclonal antibodies), or chemotherapy, within four weeks (28 days) prior to randomization. Note: Subjects who have received monoclonal antibodies for imaging are eligible * Prior receipt of investigational systemic drugs (including off-label use of approved products) or any kind of systemic treatment (chemotherapy, or immunotherapy), with the exception of hormonal therapy (HT) when given for a period not exceeding 4 weeks (28 days) prior to randomization, for treatment of inoperable, locally advanced, recurrent, or metastatic breast cancer * Prior radiotherapy to the site of cancer, if only one site will be used for evaluation of tumor response Prior use of bisphosphonates or concurrent use while on study treatment is allowed Physiological Function * Central nervous system disease or brain metastases, as documented by computed tomography (CT) or magnetic resonance imaging (MRI) * Medical or psychiatric conditions that would interfere with the ability to provide informed consent, communicate side effects, or comply with protocol requirements * Clinically significant cardiac disease, e.g., cardiac failure of New York Heart Association (NYHA) classes III-IV; uncontrolled angina pectoris, uncontrolled arrhythmia, uncontrolled hypertension, or myocardial infarction in the previous six months, as confirmed by an electrocardiogram (ECG) * Splenectomy Standard Criteria * Need for concurrent treatment with a non-permitted therapy (e.g., concurrent chemotherapy, radiotherapy, systemic immunosuppressive drugs, use of herbal medicines or botanical formulations intended to treat cancer) while on protocol therapy. Palliative radiation to painful bone lesions is allowed * Participation in another clinical study within 30 days prior to randomization * Known hypersensitivity to the study drugs * Known alcohol or drug abuse * Legal incapacity or limited legal capacity * Signs and symptoms suggestive of transmissible spongiform encephalopathy, or family members who suffer(ed) from such. * Subject who could be regarded as "vulnerable" according to International Conference on Harmonisation (ICH) Good Clinical Practice (GCP) guidelines (e.g., the subject's willingness to volunteer in a clinical trial may be unduly influenced by the expectation, whether justified or not, of benefits associated with participation, or of a retaliatory response from senior members of a hierarchy in case of refusal to participate, plus persons kept in detention; persons in nursing homes; subjects in emergency situations; homeless persons; and nomads) * Any other reason that, in the opinion of the investigator, precludes the subject from participating in this study