Study Adding Multikinase Inhibitor Sorafenib to Existing Endocrine Therapy in Patients With Advanced Breast Cancer

Inclusion Criteria:

All subjects must be female.
Age ≥ 18 years old.
Histologically proven carcinoma of the breast.
Estrogen receptor and/or Progesterone positive disease.
Metastatic or locally advanced disease.
Patients on a preexisting endocrine agent for at least 3 months before enrollment.

Have residual measurable disease after

maximal response to endocrine therapy or
no response to endocrine therapy or
progressive non-visceral disease on endocrine therapy.
Must be able to provide a tumor block from either the primary or metastatic site, if available.
Eastern Cooperative Oncology Group (ECOG) Performance Status 0-2.
Adequate organ function.

Exclusion Criteria:

Patients with rapidly progressive disease on endocrine therapy who would otherwise be candidates for chemotherapy.
Other coexisting malignancies, with the exception of basal cell carcinoma or cervical carcinoma in situ.
Prior use of anti-angiogenic agents.
As judged by the investigator, uncontrolled intercurrent illness.
Known brain metastasis. Patients with neurological symptoms must undergo a CT scan/MRI of the brain to exclude brain metastasis.
Treatment with a non-approved or investigational drug within 30 days before Day 1 of study treatment.
Concomitant use of phenytoin, carbamazepine, rifampicin, barbiturates, or St John's Wort.
Known or suspected allergy to sorafenib or any agent given in the course of this trial.
A serious non-healing wound or ulcer.
Evidence or history of bleeding diathesis or coagulopathy.
Major surgery, open biopsy or significant traumatic injury within the 4 weeks prior to the first dose of the study drug.
Pulmonary hemorrhage/bleeding event ≥ Common Toxicity Criteria for Adverse Effects (CTCAE) Grade 2 within the 4 weeks prior to the first dose of study drug.
Pregnancy
Any condition that impairs patient's ability to swallow whole pills.
Documented malabsorption problem.