Sorafenib and Anastrozole in Treating Postmenopausal Women With Metastatic Breast Cancer

PRIMARY OBJECTIVES: I. Determine the clinical benefit rate of sorafenib in combination with anastrazole in women with estrogen receptor- and/or progesterone receptor-positive metastatic breast cancer. II. Determine the recommended phase II dose of sorafenib when administered with anastrozole in these patients. SECONDARY OBJECTIVES: I. Determine the toxic effects of this regimen in these patients. II. Determine the changes in Raf-MAPK and VEGF-signaling pathways in tumor tissue and stroma before and after treatment with this regimen in these patients. OUTLINE: This is a multicenter, dose-escalation study of sorafenib. PHASE I: Patients receive oral sorafenib twice daily and oral anastrozole once daily on days 1-28. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. Cohorts of 3-6 patients receive escalating doses of sorafenib until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 6 patients experience dose-limiting toxicity. A minimum of 6 patients are treated at the MTD. PHASE II: Patients receive sorafenib at the MTD and anastrozole as in phase I. After completion of study treatment, patients are followed every 4-8 weeks.