Inclusion Criteria:

- histologically or cytologically confirmed breast cancer which is metastatic.

- A formalin-fixed paraffin embedded tumor block (preferred) or unstained slides must
be available from either a prior biopsy of the primary tumor or a metastatic site. .

- Primary tumor or metastatic biopsy lacking estrogen and progesterone receptor and
Her2 negative

- Patients must have measurable disease.

- Eastern Cooperative Oncology Group performance status 0-1.

- Patients with bone metastasis at baseline must agree to treatment with intravenous
bisphosphonates

- Subjects may have had 0-4 lines of prior systemic chemotherapy or targeted therapy
regimens administered for treatment of their metastatic breast cancer.

- Age >18 years

- Life expectancy of greater than 3 months.

- Patients must have adequate organ and marrow function as defined below:

Exclusion Criteria:

- systemic chemotherapies, targeted therapies or radiotherapy for their cancer within 2
weeks prior to entering the study

- Patients receiving any other investigational agents for breast cancer treatment.

- Patients with known brain metastases are excluded 3.2.4 History of allergic reactions
attributed to compounds of similar chemical or biologic composition to estradiol.

- Patients with any condition of the gastrointestinal tract that is expected to result
in an inability to take oral medication

- Dysfunctional or post-menopausal vaginal bleeding.

- Uncontrolled hypercalcemia/hypocalcemia

- Prior history of or active thrombophlebitis, cerebral vascular accident, myocardial
infarction, deep venous thrombosis or pulmonary embolism.

- History of or active hepatic adenoma.

- Uncontrolled intercurrent illness

- Pregnant women are excluded from this study

- Patients with bone metastasis are excluded if they are unable to receive intravenous
bisphosphonate therapy due to the risk for developing hypercalcemia.