Three Doses of TAS-108 to Treat Recurrent or Recurrent Inoperable Breast Cancer

• To evaluate the safety of TAS-108 administered on this schedule
• To investigate the comparative concentrations of TAS-108 and its metabolites in tumor tissue and blood at steady-state
• To determine the time to progression of TAS-108 administered on this schedule

This study is being done to find out how safe TAS-108 is and how well TAS-108 works on recurrent or recurrent inoperable breast cancer.

The objective of this study is to investigate the efficacy and safety of TAS-108 administered in postmenopausal patients with locally advanced or locally recurrent inoperable or progressive metastatic breast carcinoma who have previously responded to one or two standard endocrine therapies, with or without one prior chemotherapy.

Inclusion Criteria:

• Postmenopausal females
• Histologically or cytologically confirmed diagnosis of breast carcinoma
• Locally advanced or locally recurrent inoperable or metastatic breast carcinoma with documented disease progression
• Has laboratory documentation of positive estrogen receptor (ER) and/or progesterone receptor (PgR) status, and has responded to the standard first or second line hormonal anti-tumor therapy given
• Has received and whose disease progressed after one or two prior systemic hormonal anti-tumor therapies
• Performance status of greater than or equal to 2 on the Zubrod scale
• Predicted life expectancy of greater than or equal to 12 weeks
• Must give written informed consent
• Measurable disease according to the Response Evaluation Criteria in Solid Tumors (RECIST) criteria
• Absolute granulocyte count of greater than 1,500/meqL, platelet count greater than 75,000/meqL, and a hemoglobin of greater than 10 g/dL
• Adequate liver and renal function as defined by a bilirubin of less than 1.5 times the upper limit of normal and a creatinine of less than 1.5 times the upper limit of normal
• Transaminases must be less than 2.5 times the upper limit of normal except for patients with liver metastases who may have transaminases less than 5 times the upper limit of normal.
• The patient has recovered from all previous anti-cancer treatment related to toxicities to at least Grade 1.
• All previous investigational drugs must be stopped at least four weeks before commencement of treatment with TAS-108.