Vorinostat in Treating Patients With Stage IV Breast Cancer Receiving Hormone Therapy

This pilot clinical trial studies vorinostat in treating patients with stage IV breast cancer receiving hormone therapy. Vorinostat may help hormone therapy work better by making tumor cells more sensitive to the drug.

PRIMARY OBJECTIVES: I. Estimate the rate of clinical benefit (objective response plus stable disease) for patients treated with 28-day cycles of vorinostat (first 5 consecutive days each week for day 1-21) concurrent with daily aromatase inhibitor (AI) therapy (all 28 days). SECONDARY OBJECTIVES: I. Assess the safety and tolerability of vorinostat and AI combination therapy in patients with metastatic breast cancer. II. Assess the change in estrogen receptor (ER) expression, measured as the change in F-18 16 alpha-fluoroestradiol (FES) standardized uptake value (SUV) using FES positron emission tomography (PET) completed per protocol 7184 after two weeks of vorinostat and AI therapy and after 8 weeks of therapy. III. Assess tumor metabolic response, measured as the change in fludeoxyglucose F 18 (FDG) SUV using FDG PET completed per protocol 7184 after two weeks of vorinostat and AI 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), epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF) tumor expression after two weeks of vorinostat and AI therapy in patients that consent to optional tissue biopsy procedure. VI. Assess the time to progression and the overall survival of patients treated with 28-day cycles of vorinostat (first 5 consecutive days each week for day 1-21) concurrent with daily AI therapy (all 28 days). OUTLINE: Patients receive vorinostat orally (PO) 5 days a week for 3 weeks. Patients also receive AI therapy comprising either anastrozole PO daily, letrozole PO daily, or exemestane PO daily for 4 weeks. Courses repeat every 28 days in the absence of disease progression and unacceptable toxicity. After completion of study treatment, patients are followed up every 3 months for 2 years, then every 6 months until progression, and then annually thereafter.