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.