Vorinostat in Treating Patients With Stage IV Breast Cancer Receiving Aromatase Inhibitor Therapy

PRIMARY OBJECTIVES: I. Determine the rate of clinical benefit (objective response plus stable disease) for patients treated with cycles consisting of 2 weeks of vorinostat followed by 6 weeks of AI therapy. SECONDARY OBJECTIVES: I. Assess the safety and tolerability of vorinostat in patients with metastatic breast cancer. II. Assess the change in estrogen receptor (ER) expression, measured as the change in fluoroestradiol standard uptake value (FES SUV) using fluoroestradiol-positron emission tomography (FES-PET) completed per protocol 7184 after two weeks of vorinostat therapy and after 8 weeks of therapy. III. Assess tumor metabolic response, measured as the change in fluorodeoxyglucose (FDG) SUV using FDG PET completed per protocol 7184 after two weeks of vorinostat therapy and after 8 weeks of therapy. IV. Assess the change in hormone levels (estradiol, estrone, follicle-stimulating hormone \[FSH\], sex binding globulin, testosterone, and free testosterone) after 8 weeks of therapy. V. Assess the change in ER, progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), androgen receptor (AR), epithelial growth factor receptor (EGFR), vascular endothelial growth factor (VEGF) tumor expression after two weeks of vorinostat therapy in patients that consent to optional tissue biopsy procedure. VI. Assess the time to progression and the overall survival of patients treated with cycles of 2 weeks of vorinostat followed by 6 weeks of AI. OUTLINE: Patients receive vorinostat orally (PO) once daily (QD) for 2 weeks followed by AI therapy comprising anastrozole PO QD, letrozole PO QD, OR exemestane PO QD for 6 weeks. Courses repeat every 8 weeks in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up every 3 months for 2 years, every 6 months until disease progression, and then annually thereafter.