Eribulin in HER2 Negative Metastatic BrCa

Based on positive results in heavily pre-treated MBC patients, eribulin is being studied as first-line or second-line chemotherapy treatment. This is a non-randomized, open label study with participants enrolled in one of two cohorts: Cohort 1. Hormone receptor (HR)-positive/human epidermal growth factor receptor 2 (HER2)-negative (HR+/HER2-) or Cohort 2: Triple negative breast cancer (TNBC) meaning HR-negative/HER2-negative (HR-/HER2-). HR- means progesterone receptor-negative (PR-) and estrogen receptor-negative (ER-). Beyond efficacy as measured primarily by response to treatment, investigators will evaluate safety, tolerability and quality of life. In particular, it is hypothesized that eribulin may have lower rates of neuropathy, a common side effect of many of the major chemotherapeutics with activity in MBC. The investigators will study the effect eribulin has on the nerves through regular questionnaires that ask about any nerve-related symptoms. The investigators also plan to send blood samples to explore if gene markers may indicate increased sensitivity to the nerve effects of eribulin.