Inclusion Criteria:

- Female gender, and if of child-bearing potential must have negative pregnancy test
result within 2 days before enrolment and must agree to practice effective birth
control during the study.

- Aged 18 years and older.

- Histologically or cytologically confirmed invasive breast cancer with stage IIIb or
IV disease with documented progression.

- Measurable disease according to RECIST.

- Histologically documented advanced primary breast cancer or biopsy of metastatic site
demonstrating HER-2/neu expression (HER-2/neu 1+ or 2+, determined by
immunohistochemistry [IHC]). HER-2/neu 2+ patients must have a negative Fluorescence
In Situ Hybridization [FISH] test result.

- Hormone receptor status Estrogen Receptors (ERs) positive and/or Progesterone
Receptors (PRs) positive.

- No prior treatment with mouse or rat antibodies.

- Life expectancy of at least six months (if the life expectancy of a patient is
unspecified she will be allowed to enter the study).

- An Eastern Cooperative Oncology Group (ECOG) performance score of £ 1.

- Patients must have had disease progression after hormonal therapy including at least
one aromatase inhibitor.

- Adequate hematological, liver and kidney function:

- Thrombocytes ³ 100000 / mm³ (= 100 x 109 /l)

- Hemoglobin ³ 10 g/dl

- Neutrophil count ³ 1500/mm³ (= 1.5 x 109 /l)

- WBC ³ 3 X 109 /l

- Serum glutamic oxaloacetic transaminase (SGOT) and serum glutamic pyruvate
transaminase (SGPT) ≤ 2.5 x upper limit of normal (ULN)

- Serum bilirubin ≤ 2 x ULN

- Creatinine ≤ 1.5 x ULN or clearance ³ 60 ml/min

- No life-threatening visceral disease.

- No known brain or central nervous system metastases.

- No symptomatic pleural effusions.

- No symptomatic pericardial effusions.

- No subjects whose only site of metastatic involvement is bone metastases with the
exception of those with a measurable soft tissue component of the bone lesion seen
with imaging that does not require palliative radiation intervention and/or the
patient has a lytic bone lesion ³ 1 cm measured with radiography that can be followed
for evidence of re-calcification.

- No history of relevant cardiovascular disease:

- LVEF within the institutional ranges of normal as measured by echocardiogram or
MUGA scan

- No prior uncontrolled or symptomatic congestive heart failure NYHA ³ 2

- No myocardial infarction within the past two years

- No uncontrolled or symptomatic cardiac arrhythmias

- No severe dyspnea.

- No pulmonary dysfunction or need for continuous supportive oxygen inhalation.

- No other concurrent uncontrolled co-morbid illness.

- No other concurrent malignancy, except treated basal cell or squamous cell carcinoma
of the skin, or in situ carcinoma of the cervix.

- Patients with documented autoimmune diseases (such as lupus) are excluded from
participation in the study unless a waiver is granted by the responsible medical
monitor.

- Patients with a human immunodeficiency virus, hepatitis B or hepatitis C positive
status are excluded from participation in the study.

- No prior or concurrent chemotherapy regimen for advanced or metastatic disease.

- Prior neo-adjuvant or adjuvant chemotherapy is allowed provided it was stopped at
least six months before study entry.

- No concurrent hormone therapy (hormone therapy must be stopped at the screening
visit).

- At least 4 weeks since prior radiotherapy.

- No concurrent immune therapy.

- No concurrent corticosteroid therapy.

- No regularly used medication for a health condition or comorbidity that might result
in undue risk to the patient.

- No prior investigational treatment for advanced or metastatic disease.

- Able and willing to comply fully with the protocol.