Inclusion Criteria:

- Histologically- or cytologically- confirmed metastatic breast adenocarcinoma

- Age 18-75 years

- HER2 status positive according to the local institution reported grade 3+ staining
intensity (on a scale of 0 to 3) by means of immunohistochemical analysis or grade 2+
staining intensity by means of immunohistochemical analysis with gene amplification
on fluorescence in situ hybridization

- Previous therapies had to include, regimens containing an anthracycline and a taxane

- Previous treatment with trastuzumab, alone or in combination with chemotherapy for
locally advanced or metastatic disease, is required

- Measurable disease as defined by the presence of at least one measurable lesion
(except bone metastases, ascites or pleural effusions)

- Performance status (WHO) 0-2

- Adequate liver (serum bilirubin <1.5 times the upper normal limit; AST and ALT <2.5
times the upper normal limit in the absence of demonstrable liver metastases, or <5
times the upper normal limit in the presence of liver metastases); adequate renal
function (serum creatinine <1.5 times the upper normal limit); and bone marrow
(neutrophils ≥ 1.5x 109 /L, and platelets ≥ 100x 109 /L) function

- No radiation of measurable disease (except brain metastases)

- No progressive brain metastases according to clinical or radiological criteria

- No brain metastases without prior radiation therapy

- Written informed consent

Exclusion Criteria:

- Patient unable to take oral medication

- Active infection

- History of significant cardiac disease (unstable angina, congestive heart failure,
myocardial infarction within the previous 6 months, ventricular arrhythmias)

- Other invasive malignancy except nonmelanoma skin cancer

- Psychiatric illness or social situation that would preclude study compliance

- Pregnant or lactating women