Inclusion Criteria:

          -  Histologically or cytologically confirmed and documented adenocarcinoma of the breast
             with metastatic or locally recurrent disease not amenable to curative resection.
             Patients with measurable and/or non-measurable disease evaluable according to Response
             Evaluation Criteria in Solid Tumors (RECIST), Version 1.1 are eligible.

          -  HER2-positive disease (defined as either immunohistochemistry [IHC] 3 + or in situ
             hybridization [ISH] positive) as assessed by local laboratory on primary tumor or
             metastatic site if primary tumor not available

          -  Eastern Cooperative Oncology Group (ECOG) Performance Status 0 or 1

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

          -  Negative serum pregnancy test result at baseline and use of effective contraception as
             defined by the protocol

        Exclusion Criteria:

          -  Previous systemic non-hormonal anti-cancer therapy for the metastatic or locally
             recurrent disease. Note: Prior to study entry, up to two lines of hormonal therapy for
             metastatic or locally recurrent disease are permitted, one of which may be in
             combination with everolimus.

          -  Disease-free interval of less than 6 months from completion of adjuvant or neoadjuvant
             systemic non-hormonal treatment to recurrence of breast cancer

          -  Previous approved or investigative anti-HER2 agents as neoadjuvant or adjuvant therapy
             for any breast cancer treatment, except Herceptin

          -  History of persistent Grade 2 or higher hematological toxicity resulting from previous
             adjuvant or neoadjuvant therapy

          -  Radiographic evidence of central nervous system (CNS) metastases as assessed by
             computed tomography (CT) or magnetic resonance imaging (MRI), unless they have been
             treated and have been stable for at least 3 months and do not require ongoing
             corticosteroid treatment

          -  Current peripheral neuropathy of Grade 3 or greater

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

          -  Inadequate organ function

          -  Uncontrolled hypertension with or without medication

          -  Clinically significant cardiovascular disease

          -  History of LVEF decline to below 50% during or after prior Herceptin neo-adjuvant or
             adjuvant therapy

          -  Current known infection with HIV, hepatitis B virus, or hepatitis C virus

          -  Severe uncontrolled concomitant disease that would contraindicate the use of any of
             the investigational drugs used in this study or that would put the patient at high
             risk for treatment-related complications, including severe pulmonary
             conditions/illness

          -  Pregnant or lactating women

          -  Dyspnea at rest due to complications of advanced malignancy or other disease requiring
             continuous oxygen therapy

          -  History of receiving any investigational treatment within 28 days prior to first dose
             of study drug administration (dosing) or concurrent participation in any
             interventional clinical trial