Inclusion Criteria:

          -  HER2 positive breast cancer or gastric cancer that is resistant to standard therapy or
             for which no standard therapy is available (Part 1A only)

          -  HER2 positive and negative breast cancer (Part 2A)

          -  HER2 negative breast cancer (Part 1B & Part 2B)

          -  Performance status of 0 or 1

          -  Adequate bone marrow, kidney and liver function

        Exclusion Criteria:

          -  Known CNS disease including, but not limited to, metastases

          -  History of exposure to certain cumulative doses of anthracyclines

          -  Grade 3 or higher hypersensitivity reaction to prior receipt of any antibody therapy

          -  Active and clinically significant bacterial, fungal, or viral infection

          -  Abnormal cardiac function defined by a LVEF <50% by ECHO or MUGA

          -  Patients with previous history or active interstitial lung disease or pulmonary
             fibrosis, or a history of other clinically significant lung diseases