Inclusion Criteria:

- Confirmed stage IV or recurrent breast cancer

- positive for HER2 in tumor cells by immunohistochemistry (3+) or FISH

- Eastern Cooperative Oncology Group (ECOG) performance status 0-1

- Age ≥ 20 years

- Measurable or evaluable disease according to the Response Evaluation Criteria in
Solid Tumors version 1.1

- Patients who were treated with anthracycline based regimens in the adjuvant or
metastatic setting.

- Patients who experienced disease progression after the treatment with lapatinib
containing regimens whose response were more than stable disease (including CR, PR,
SD≥ 12 weeks) during treatment. There is no limitation on the time interval between
the stop of lapatinib treatment and the study enrollment.

- Patients must have received 2 lines of prior anti-HER2 therapy in metastatic setting
as follows regardless of the order In case with trastuzumab: monotherapy or combined
with taxane or combined with AI In case with lapatinib: monotherapy or combined with
capecitabine or combined with aromatase inhibitors Patients who experienced a disease
recurrence during the adjuvant trastuzumab treatment or within 6 months after the
completion of adjuvant trastuzumab treatment are allowed not to receive trastuzumab
treatment in the metastatic setting.

- Central nervous system metastasis is permitted if asymptomatic or controlled with
minimal steroid requirement and is documented to be non-progressing at study entry.

- Negative urine pregnancy test within 7 days prior to registration in premenopausal
patients

- Baseline LVEF ≥50% measured by echocardiogram or multiple gated acquisition scan
(MUGA) scan

- Adequate hematopoietic function: Absolute granulocyte count ≥1,500/mm3,
platelet≥100,000/mm3, hemoglobin≥10g/mm3

- Adequate hepatic function: total bilirubin ≤1.5mg/dL, AST/ALT≤2 x upper normal limit
(UNL), alkaline phosphatase ≤2.5 x UNL, in case with bone metastases alkaline
phosphatase ≤5 x UNL

- Adequate renal function: Serum creatinine ≤1.5mg/dL

- Ability to understand and comply with protocol during study period

- Patients should sign a written informed consent before study entry

Exclusion Criteria:

- Pregnant or lactating women or women of childbearing potential, including women whose
last menstrual period was ,12 months ago (unless surgically sterile) who are unable
or unwilling to use adequate contraceptive measures during the study treatment
period.

- Patients who received vinorelbine treatment in metastatic setting.

- Patients who received more than 2 lines of prior anti-HER2 therapy in metastatic
setting

- Patients who have history of cancer other than in situ uterine cervix cancer or
nonmelanotic skin cancer

- Patients with GI tract disease resulting in an inability to take oral medication,
malabsorption syndrome, a requirement for IV alimentation, prior surgical procedures
affecting absorption, uncontrolled GI disease (e.g., Crohn's disease, ulcerative
colitis)

- current active hepatic or biliary disease (with exception of patients with Gilbert's
syndrome, asymptomatic gallstones, liver metastases or stable chronic liver disease
per investigator assessment)

- Concurrent disease or serious medical disorder,

- Serious cardiac illness :

History of documented congestive heart failure (CHF) or systolic dysfunction (LVEF <50%)
High-risk uncontrolled arrhythmias (ventricular tachycardia, high-grade atrioventricular
(AV)-block,supraventricular arrhythmias, prolonged corrected QT (QTc) which are not
adequately rate-controlled) Angina pectoris requiring antianginal medication Clinically
significant valvular heart disease Evidence of transmural infarction on ECG Poorly
controlled hypertension (e.g. systolic >180mm Hg or diastolic >100mm Hg)

- known immediate or delayed hypersensitivity reaction or idiosyncrasy to drugs
chemically related to any of the study agents or their excipients.