Inclusion Criteria:

- Adult male or female patients, >/= 18 years of age

- Histologically or cytologically confirmed adenocarcinoma of the breast with
metastatic or locally recurrent disease not amenable to curative resection

- HER2-positive breast cancer

- Eastern cooperative Oncology Group (ECOG) performance status 0, 1 or 2

- Left ventricular ejection fraction (LVEF) of at least 50%

Exclusion Criteria:

- Previous systemic non-hormonal anti-cancer therapy for metastatic or locally
recurrent disease

- Disease-free interval from completion of adjuvant or neoadjuvant systemic
non-hormonal treatment to recurrence
- Previous approved or investigative anti-HER2 agents in any breast cancer treatment
setting, except for trastuzumab and/or lapatinib in the adjuvant or neoadjuvant
setting

- Disease progression while receiving trastuzumab and/or lapatinib in the adjuvant or
neoadjuvant setting

- History of persistent Grade 2 or higher (NCI-CTC, Version 4.0) hematological toxicity
resulting from previous adjuvant or neoadjuvant therapy

- Central nervous system (CNS) metastases

- Current peripheral neuropathy of Grade 3 or greater (NCI-CTC, version 4.0)

- History of other malignancy within the last 5 years prior to 1st study drug
administration, except for carcinoma in situ of the cervix or basal cell carcinoma

- Inadequate bone marrow, liver or renal function

- Uncontrolled hypertension

- Hepatitis B, hepatitis C or HIV infection