Combination of Oral WX-671 Plus Capecitabine vs. Capecitabine Monotherapy in First-line Her2-negative Metastatic Breast Cancer

Inclusion Criteria:

* Females aged ≥ 18 years
* Patients appropriate for palliative first-line, mono chemotherapy with capecitabine
* Histological or cytological confirmed, non-inflammatory metastatic breast cancer
* Availability of paraffin-embedded tumor tissue from the primary resection or biopsy of a metastatic lesion.
* HER2-negative breast cancer
* Complete staging within 2 weeks prior to randomization (4 weeks for bone scan).
* Radiologically confirmed disease
* ECOG performance status of ≤ 2
* Ability to understand and willingness to voluntarily sign and date a written informed consent form before screening
* Negative pregnancy test (urine or serum) within 3 days before first study drug for women of childbearing potential. Use of effective contraception during the study and for 3 months after stopping study drug treatment.
* Normal organ and marrow function as defined by laboratory parameters (obtained within the screening period) within the following limits:

  * neutrophils \>= 1.5 x 109/L;
  * platelets \>= 100 x 109/L;
  * hemoglobin \>= 9.0 g/dL (5.6 mmol/L).
  * total bilirubin \<= 1.5 x upper limit of normal (ULN);
  * aspartate aminotransferase (AST)/ALT \<= 2.5 x ULN (\< 5.0 x ULN for patients with liver metastases);
  * serum creatinine \<= 2 x ULN, or calculated creatinine clearance \>45 mL/min according to Cockroft and Gault formula).

Exclusion Criteria:

* Endocrine therapy completed within 2 weeks before the start of treatment (i.e. previous hormone therapy is allowed provided that there is a washout period of 2 weeks).
* Prior chemotherapy or biologic therapy for metastatic disease.
* Major surgery within 4 weeks prior to the start of treatment.
* Other anti-cancer treatment (e.g. hormones) within 2 weeks before the start of treatment.
* Treatment within 12 months with adjuvant 5-FU containing chemotherapy (regarded as indicating 5-FU resistance) and/or prior capecitabine therapy.
* Radiation therapy. Palliative radiation of stable, non-target lesions more than 2 weeks before the start of treatment is allowed, provided patients have recovered from the radiation side-effects.
* History of or radiological evidence of brain metastasis including previously treated, resected or asymptomatic brain lesions or leptomeningeal involvement.
* Active seizure disorder or history of cerebrovascular accident (CVA) or transient ischemic (TI) attack within the past 12 months.
* History of other malignancy within the last 3 years except for surgically cured non-melanoma skin cancer or cervical carcinoma in situ.
* Active cardiac disease e.g. unstable angina, congestive heart failure, myocardial infarction (MI) within the preceding 6 months.
* Any medical condition prohibiting standard imaging procedures
* Pregnant or breast-feeding.
* Any unrelated illness, e.g. active infection requiring parenteral antibiotics, inflammation, medical condition or laboratory abnormalities, which in the judgment of the investigator might significantly affect patients' study participation.
* Any surgical or medical condition that might significantly alter the absorption, distribution, metabolism or excretion of either study drug.
* Known hepatitis B/C or HIV (human immunodeficiency virus) infection.