A Study of E7389 in Advanced/Metastatic Breast Cancer Patients

The primary objective is to determine the response rate (RR) to E7389 monotherapy administered as an IV bolus of 1.4 mg/m\^2 on Days 1, 8, and 15 of a 28-Day cycle and on Days 1 and 8 of a 21-day cycle in patients with advanced/metastatic breast cancer treated with chemotherapy including an anthracycline and a taxane, with previously documented progression during or within six months following the last dose of prior chemotherapy. The secondary objectives are to evaluate: * The safety and tolerability of E7389 monotherapy in this patient population; * The antitumor activity of E7389 as determined by duration of response, time to progression, and overall survival; * Quality of life measured by the Functional Assessment of Cancer Therapy-Breast (FACT-B) questionnaire/tumor-related symptom improvement or worsening measured by pain intensity on a visual analog scale (VAS), analgesics consumption, weight changes and performance status (PS); * Tumor pharmacogenetics and their possible relationship to response (assessment of beta-tubulin isotype mRNA on biopsy sample) in patients who have signed a separate consent form