Inclusion Criteria:

- Histologically documented, incurable, locally advanced or metastatic breast cancer

- Evaluable or measurable HER2-positive disease

- History of progression during or within 60 days after treatment with any prior
trastuzumab-containing chemotherapy regimen for HER2-positive breast cancer

- Previous treatment with chemotherapy for MBC

Exclusion Criteria:

- History of significant cardiac disease, unstable angina, CHF, myocardial infarction,
or ventricular arrhythmia requiring medication

- History of Grade ≥ 3 hypersensitivity reaction to trastuzumab

- History of any toxicity to trastuzumab that resulted in trastuzumab being permanently
discontinued

- Symptomatic brain metastases or any radiation or surgery for brain metastases within
3 months of first study treatment

- Require supplemental oxygen for daily activities

- Grade ≥ 2 peripheral neuropathy

- Bisphosphonate therapy for symptomatic hypercalcemia

- Any chemotherapy, hormonal therapy, radiotherapy, immunotherapy, or biologic therapy
for the treatment of breast cancer within 4 weeks of first study treatment

- Any experimental therapy within 4 weeks of first study treatment

- Any major surgical procedure within 4 weeks of first study treatment

- History of clinically symptomatic liver disease, including viral or other hepatitis,
current or history of alcoholism, or cirrhosis

- Pregnancy or lactation