Study in Women With Metastatic Breast Cancer Whose Cancer Has Gotten Worse After Anthracycline and Taxane Therapy

Inclusion Criteria: * Locally advanced or metastatic breast cancer not amenable to surgery or radiation with curative intent * Must have received any chemotherapy regimen in the past * Evidence of tumor resistance to last chemotherapy defined as progression after 6 months of previous chemotherapy for advanced disease * Must have measurable (by imaging techniques) disease * Adequate bone marrow, liver and renal function * Must provide evidence of informed consent and willingness and ability to comply with scheduled visits, treatment plan and study procedures. Exclusion Criteria: * Received more than 2 prior chemotherapy regimens for metastatic disease * Received in the past another drug of the same class as the investigational drug, i.e. topoisomerase I inhibitor * Enrolled in another clinical intervention study * Pregnancy, breast feeding, fertile women refusing to use reliable contraceptive methods * Cardiac or thrombotic event in the last 12 months * Brain metastases