Schedules of Nab-Paclitaxel in Metastatic Breast Cancer

Inclusion Criteria: * Histologically or cytologically confirmed HER2-negative metastatic (stage IV) breast cancer. * Measurable or non-measurable, but radiologically evaluable, disease according to RECIST 1.1 criteria. * Female aged 18 years or older. * Life expectancy \> 3 months. * Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1. * Either ER-positive or ER-negative disease. Patients with ER-positive disease must be endocrine resistant, defined as having failed at least one prior endocrine therapy for breast cancer, or must be candidates for first-line chemotherapy. * If previously treated with a taxane or anthracycline in the neoadjuvant or adjuvant setting, the period from end of treatment to disease recurrence must have been \> 12 months (\> 365 days). * Radiation therapy, if given and regardless of site, must be completed at least 2 weeks prior to randomization. * Normal hematologic status. * Normal renal function. * Normal liver function. * Normal cardiac function. * Women of childbearing potential: documented negative pregnancy test within 2 weeks prior to randomization, and acceptable birth control during the duration of the trial therapy and for a period of 6 months following the last administration of study drug. * Written Informed Consent (IC) must be signed and dated by the patient and the Investigator prior to randomization. * Completed baseline Quality of Life Form. * The patient has been informed of and agrees to data transfer and handling, in accordance with national data protection guidelines. * Availability of an formalin fixed paraffin embedded (FFPE) block from the primary tumor (breast lesion) for submission to central pathology review and for translational research. * Written consent to pathology material submission, signed and dated by the patient and the Investigator prior to randomization. Exclusion Criteria: * Any prior chemotherapy for metastatic breast cancer. * Presence of central nervous system (CNS) metastasis. * Peripheral neuropathy grade 2 or higher (CTCAE version 4). * Significant uncontrolled cardiac disease (i.e. unstable angina, recent myocardial infarction within prior 6 months), patients classified as having a New York Heart Association (NYHA) class III or IV congestive heart failure. * Pregnant or lactating. * Prior history of non-breast malignancy (except for adequately controlled basal cell carcinoma of the skin, carcinoma in situ of the cervix, in situ carcinoma of the bladder). * Any concurrent condition which in the Investigator's opinion makes it inappropriate for the patient to participate in the trial or which would jeopardize compliance with the protocol. * Contraindications or known hypersensitivity to the study medication or excipients. * The use of any anti-cancer investigational agents within 30 days prior to expected start of trial treatment. * Inability or unwillingness to abide by the study protocol or cooperate fully with the Investigator.