Inclusion Criteria:

          -  Female, age ≥ 18 years.

          -  Histologic or cytologic diagnosis of breast carcinoma.

          -  Part A: T1-4 breast cancer with measurable primary breast tumor, defined as palpable
             tumor with both diameters 2.0cm or greater as measured by caliper. Newly diagnosed
             metastatic patients with measurable primary breast tumor ≥2cm are eligible provided
             that there are plans for toilet mastectomy after completing 14 weeks of pre-operative
             drug therapy. Patients must not have received prior chemotherapy or hormonal therapy
             for the treatment of the current breast cancer.

          -  Part B: Patients with metastatic breast cancer with measurable tumor by RECIST
             criteria.Patients previously treated with letrozole are eligible if they progressed on
             letrozole ≥1 year after adjuvant treatment, or ≥ 6 months in the metastatic setting.

          -  ECOG 0-1.

          -  Estimated life expectancy of at least 12 weeks.

          -  Adequate organ function including the following:

               -  Bone marrow:

               -  Absolute neutrophil (segmented and bands) count (ANC) ≥ 1.5 x 109/L

               -  Platelets ≥ 100 x 109/L

               -  Hepatic:

               -  Bilirubin ≤ 1.5 x upper limit of normal (ULN),

               -  ALT or AST ≤ 2.5x ULN, (or ≤5 X with liver metastases)

               -  Renal:

        Creatinine ≤ 1.5x ULN

        • Post-menopausal women. Post-menopausal status is defined either by

          -  Age ≥ 60 years and one year or more of amenorrhea

          -  Age < 60 years and one year or more of amenorrhea (in the absence of ovarian
             suppression) and with estradiol and FSH levels consistent with menopause, *Treatment
             with a luteinizing hormone-releasing hormone (LHRH) agonist (goserelin acetate or
             leuprolide acetate) is not permitted for induction of ovarian suppression for Part A
             (patients with non-metastatic disease receiving the study treatment as neoadjuvant
             therapy).

        However, in Part B (patients with metastatic disease), pre-menopausal women who are treated
        with medical ovarian suppression with post-menopausal levels of estradiol (institutional
        limits) at time of study entry and who will continue to be suppressed with 4-weekly LHRH
        agonist during study treatment may be enrolled. If these patients were previously on
        12-weekly long-acting LHRH agonist, this has to be switched to 4-weekly LHRH agonist while
        the patient is on study treatment.

        • Signed informed consent from patient or legal representative.

        Exclusion Criteria:

          -  Treatment within the last 30 days with any investigational drug.

          -  Concurrent administration of any other tumor therapy, including cytotoxic
             chemotherapy, hormonal therapy, and immunotherapy.

          -  Major surgery within 28 days of study drug administration.

          -  Active infection that in the opinion of the investigator would compromise the
             patient's ability to tolerate therapy.

          -  Pregnancy.

          -  Breast feeding.

          -  Serious concomitant disorders that would compromise the safety of the patient or
             compromise the patient's ability to complete the study, at the discretion of the
             investigator.

          -  Active bleeding disorder or bleeding site.

          -  Non-healing wound.

          -  Poorly controlled diabetes mellitus.

          -  Second primary malignancy that is clinically detectable at the time of consideration
             for study enrollment.

          -  Symptomatic brain metastasis.

          -  History of significant neurological or mental disorder, including seizures or
             dementia.