RecruitingPhase 2Drug trialTucatinib+Trastuzumab+Eribulin in HER2+ MBCThe purpose of this study is to evaluate the safety and efficacy of the three-drug combination of tucatinib, trastuzumab, and eribulin in patients with de novo and recurrent unresectable metastatic HER-2/neu positive breast cancer as assessed by ORR, PFS and OS after prior treatment with a taxane, trastuzumab, and T-DM1.