Eribulin Mesylate in Treating Patients With Previously Treated Metastatic Breast Cancer

PRIMARY OBJECTIVES: I. Progression free survival (PFS). SECONDARY OBJECTIVES: I. Frequency of alopecia with absence or decrease to \< 50%. II. Incidence of grade 3 and 4 neutropenia of \< 30%. III. Incidence of sensory neuropathy (all grades) to \< 25%. TERTIARY OBJECTIVES: I. Assess the role of circulating endothelial cell precursors (CEPs) and apoptotic circulating endothelial cells (CECs), in predicting early response to treatment. OUTLINE: Patients receive eribulin mesylate intravenously (IV) over 2-5 minutes on days 1, 8, and 15. Courses repeat every 4 weeks in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up for 1 year.