Phase II Trial of SAHA & Tamoxifen for Patients With Breast Cancer

Inclusion Criteria: * Patients must have cytologically/histologically documented locally advanced or metastatic breast cancer with either: 1. Progression on treatment with any aromatase inhibitor for metastatic disease; 2. Recurrence while on adjuvant aromatase inhibitors or within 12 months of completion; 3. Recurrence after having completed adjuvant tamoxifen for at least 12 months; 4. Patient who are not candidates for or are intolerant of aromatase inhibitor treatment; 5. Patients are allowed (but not required) to have one prior chemotherapy regimen for metastatic disease. * Tumors must express estrogen or progesterone receptor. * Patients are eligible regardless of the menopausal status. * Age \> 18 years old * Patients must have Eastern Cooperative Oncology Group (ECOG) performance status 0-2. * Patients must be able to give informed consent and able to follow guidelines given in the study. * Patients must have acceptable organ function, as defined by the following laboratory parameters: white blood count (WBC) \>3.0 x 10\^9/L; absolute neutrophil count (ANC) \>1.5 x 10\^9/L; hemoglobin (Hgb) \>10.0g/dL; platelets (PLT) \>100 x 10\^9/L, Bilirubin \< 2.0 mg/dl, aspartate aminotransferase/alanine aminotransferase (AST/ALT) \< 2.5 X upper limit of normal (ULN), Creatinine \<1.8 mg/dl (Creatinine clearance \>60 ml/min). * Women of childbearing age must have a negative pregnancy test. All patients of reproductive potential must use an effective method of contraception during the study and 6 months following termination of treatment. (Not applicable to patients with bilateral oophorectomy and/or hysterectomy or to female patients who are older than 50 years and have not had a menstrual cycle in more than one year. * Patients must have measurable disease by RECIST criteria by staging studies performed within 30 days of enrollment. For patients with bone only disease: For this protocol isolated bone lesions can be classified as target lesions if they are measurable by MRI at screening and must be followed by MRI. * Both men and women of all races and ethnic groups are eligible for this trial. Exclusion Criteria: * Patients must not have received tamoxifen for metastatic disease. * Patients must not have evidence of significant active infection (e.g., pneumonia, cellulitis, wound abscess, etc.) at time of study entry. * Patients must be disease-free of prior invasive malignancies for \> 5 years with the exception of: curatively-treated basal cell or squamous cell carcinoma of the skin, carcinoma in situ of the cervix. * Pregnant and breast-feeding women are excluded from the study because effects on the fetus are unknown and there may be a risk of increased fetal wastage. * Patients with uncontrolled central nervous system (CNS) metastasis or a history of seizures are excluded. Patients with stable CNS metastasis (either surgically resected, treated with gamma knife or stable for 3 months following whole brain radiation therapy \[WBRT\] are eligible). Patients with stable brain metastases will need an MRI within 4 weeks prior to start of therapy. * Patients may not be receiving any other investigational agents and must have stopped all other histone deacetylase inhibitors (including Valproic acid) or other hormonal therapies. * Patients must have discontinued their prior therapies for breast cancer and radiation therapy for a minimum of 3 weeks, patient is excluded if radiation therapy was given to a single measurable lesion and the disease is otherwise not measurable. * Patients are excluded if they have any known hypersensitivity reaction to tamoxifen. * Patient with a history of blood clots are not eligible. * Women who have abnormal vaginal bleeding and/or endometrial hyperplasia or cancer are not eligible. * Patients with evidence of visceral crisis are not eligible for this study.