The purpose of this clinical trial is to determine if RPR109881 is a better treatment than capecitabine (Xeloda) for advanced breast cancer in patients that no longer benefit from docetaxel and/or paclitaxel.

All patients in this trial will receive either the investigational drug or capecitabine, a chemotherapy drug that is already approved to treat your disease. These drugs prevent tumor cells from dividing, so they may stop growing or die. The investigational drug in this clinical trial is a chemotherapy drug given through the vein once every three weeks. Patients who receive capecitabine will receive this drug by mouth for 14 days, every 21 days.

Eligibility Criteria

In order to be eligible for this trial you must:

• Have a diagnosis of breast cancer that is now metastatic (meaning the cancer has spread beyond its original location) or a recurrence of the cancer in its original location that cannot be removed by surgery.
• Have received previous treatment with anthracyclines (e.g., adriamycin, Doxorubicin) and taxanes (e.g., paclitaxel, docetaxel, Taxol®, Taxotere®) for your breast cancer and your doctor has determined that these treatment are no longer of benefit to you.
• Be at least 18 years of age.
• Not be taking other treatments for your cancer at the time you enter this trial.
• Not be pregnant.

Additionally, there are other criteria for study entry that a doctor participating in this study will need to review in detail with you and clinical assessments may need to be performed (e.g., lab tests, CT scans).