Statement: Completely disabled patients, totally confined to bed or chair and unable to carry on any selfcare are eligible for the primary trial but excluded from the secondary trial.
Primary_evidence: Inclusion Criteria:   Women  20 years   Histologically or cytologically confirmed diagnosis of adenocarcinoma originating in the breast Exclusion Criteria:   Number of prior chemotherapy lines of treatment in the metastatic setting 3
Secondary_evidence: Inclusion Criteria:   Adult participants >/=18 years of age   HER2-positive breast cancer   Histologically or cytologically confirmed adenocarcinoma of the breast with locally recurrent or metastatic disease, and be a candidate for chemotherapy. Participants with locally advanced disease must have recurrent or progressive disease, which must not be amenable to resection with curative intent.   Participants must have measurable and/or non-measurable disease which must be evaluable per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1   Eastern Cooperative Oncology Group (ECOG) Performance Status 0 or 1   Adequate organ function as determined by laboratory results Exclusion Criteria:   History of prior (or any) chemotherapy for metastatic breast cancer or recurrent locally advanced disease   An interval of <6 months from the last dose of vinca-alkaloid or taxane cytotoxic chemotherapy until the time of metastatic diagnosis   Hormone therapy <7 days prior to randomization   Trastuzumab therapy and/or lapatinib (neo- or adjuvant setting) <21 days prior to randomization   Prior trastuzumab emtansine or pertuzumab therapy