Breast cancer is the most common form of cancer among women in developing countries, accounting for approximately one-fifth of all female cancers in the United States. Although mortality rates are declining in some countries, it remains the leading cause of death in women aged 40-55 years. The median survival for women with metastatic breast cancer is 2-3 years but there is significant variability in this population. The primary goals of treatment in patients with metastatic breast cancer are improvement or maintenance of quality of life and prolongation of survival. The taxanes, paclitaxel and docetaxel, were incorporated into the treatment of metastatic breast cancer in the 1990's. The usefulness of the taxanes is limited by the development of tumor resistance to these agents. This phase II trial with BAY59-8862 will be conducted to determine the anti-tumor efficacy of BAY59-8862 in taxane-resistant metastatic breast cancer.