In view of the potency of tucatinib for the treatment of brain metastases and its modest toxicity, it is important to evaluate the combination of this drug with other established anti-HER2 therapies. There remains a need to evaluate the efficacy of tucatinib with additional active agents in this area. Given the demonstrated activity of eribulin in metastatic breast cancer in general and in her2 positive disease combined with trastuzumab in particular, this study proposes to evaluate the safety and efficacy of the three-drug combination of eribulin, trastuzumab, and tucatinib. It is also important to ascertain the activity of this combination in patients who have previously received tucatinib, as little is known about whether resistance to tucatinib plus one chemotherapy drug confers resistance to tucatinib with a different partner drug.
The 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.