Eribulin is a novel microtubule inhibitor with mitotic and nonmitotic mechanisms of action. Both pooled and subgroup analyses from large-scale Phase III clinical trials demonstrated that eribulin has substantial activity in patients with pretreated (anthracycline and a taxane) advanced or metastatic breast cancer. We review recent pharmacological and clinical findings pertaining to eribulin use in metastatic breast cancer -particularly highlighting eribulin in difficult-to-treat and aggressive disease, and safety data in specific patient populations. Additionally, recent advancements in our understanding of the mechanism of action of eribulin and potential future directions for its clinical development are discussed. Ongoing studies of eribulin in combination with immunotherapies and established cytotoxic agents may help shape the future landscape of breast cancer treatment.Lay abstract: Eribulin, a nontaxane microtubule inhibitor, is approved for the treatment of metastatic breast cancer. In this review, we present the clinical activity and safety of eribulin in metastatic breast cancer -highlighting studies investigating efficacy and tolerability in some aggressive, difficult-to-treat breast cancer populations.