Inclusion Criteria:

Patients must fulfill all the following criteria:

- Females aged 18 to 70 years-old.

- Willingness to participate in the study and comply with its procedures.

- Documented diagnosis of metastatic breast carcinoma (stage IV) Human Epidermal Growth
Factor Receptor 2 (HER2) overexpressing (Immunohistochemistry (IHC) 3+ or
Fluorescence In Situ Hybridization(FISH) +).

- No prior chemotherapy for metastatic breast cancer.

- Adjuvant or neo-adjuvant chemotherapy is allowed according to the following rules:

- patients treated with anthracyclines if all the following conditions are met:

- Doxorubicin total dose <= 300 mg/m^2

- Epirubicin total dose <= 480 mg/m^2

- Chemotherapy-free interval of > 12 months

- no taxane-based adjuvant or neo-adjuvant chemotherapy is allowed;

- patients treated with non-anthracycline/taxane adjuvant or neo-adjuvant
chemotherapy regimens are freely eligible (i.e.
cyclophosphamide/methotrexate/fluorouracil (CMF) or similar regimens).

- At least one measurable lesion according to RECIST criteria.

- Complete hematologic and biologic baseline evaluation within 2 weeks prior to start
of treatment.

- Complete Tumor baseline evaluation including a total body computed tomography (CT)
scan within 4 weeks prior to start of treatment.

- Left ventricular ejection fraction (LVEF) >= 50% as determined by echocardiogram or
Multi Gated Acquisition (MUGA) scan.

- World Health Organization (WHO) performance status 0,1.

- Life expectancy > 3 months.

- Laboratory requirements :

- Hematology :

- Neutrophils > 1.5 x 10^9/L

- Platelets > 100 x 10^9/L

- Hemoglobin > 10 g/dL

- Hepatic function:

- Total bilirubin <= 1.25 x the upper-normal limits (UNL);

- ASAT (Aspartate Aminotransferase or SGOT), ALAT (Alanine aminotransferase
or SGPT) <= 2.5 x the upper-normal limits;

- For patients with liver metastases:

- Total bilirubin < 1.5 x the UNL (Upper limit of normal) ;

- ASAT and/or ALAT < 3 x the UNL;

- Renal function :

- Serum Creatinine < 1.5 x the UNL.

- Women of child bearing potential must have a negative serum pregnancy test and be
using adequate contraception.

- Patients must be accessible for treatment and follow-up.

Exclusion Criteria:

Patients will not be enrolled if any of the following criteria apply:

- Prior chemotherapy for metastatic disease.

- History of prior malignancy in the last 10 years (other than non melanoma skin cancer
or excised cervical carcinoma in situ).

- Radiation to disease areas within 3 weeks of study initiation.

- Symptomatic peripheral neuropathy > grade 2 according to the National Cancer
Institute (NCI) Common Toxicity Criteria.

- Other serious illness or medical condition.

- LVEF < 50% as determined by echocardiogram or MUGA scan.

- Congestive hearth failure or angina pectoris even if it is medically controlled.
Previous history of myocardial infarction within 1 year from study entry,
uncontrolled high risk hypertension or arrhythmia.

- History of significant neurologic or psychiatric disorders including dementia or
seizures.

- Active infection.

- Active peptic ulcer, unstable diabetes mellitus or other contraindications for the
use of dexamethasone.

- Concurrent treatment with other experimental drugs. Participation in another clinical
trial with any investigational drug within 30 days prior to study screening.

- Concurrent treatment with corticosteroids used for reasons other than for
premedication. However patients receiving chronic treatment with corticosteroids (>
6 months) at low dose (< 20 mg of methylprednisolone or equivalent dose of other
corticosteroids) for whichever reason are eligible.

- Taxane-based adjuvant or neo-adjuvant chemotherapy < 12 months.

- Other concurrent chemotherapy, immunotherapy, radiotherapy or any other
investigational medication, for the treatment of the tumor.

- Pregnant or breast-feeding women.