Journal of clinical oncology : official journal of the American Society of Clinical Oncology
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The antibody-drug conjugate trastuzumab-DM1 (T-DM1) combines the biologic activity of trastuzumab with targeted delivery of a potent antimicrotubule agent, DM1, to human epidermal growth factor receptor 2 (HER2)-overexpressing cancer cells. Based on results from a phase I study that showed T-DM1 was well tolerated at the maximum-tolerated dose of 3.6 mg/kg every 3 weeks, with evidence of efficacy, in patients with HER2-positive metastatic breast cancer (MBC) who were previously treated with trastuzumab, we conducted a phase II study to further define the safety and efficacy of T-DM1 in this patient population. ⋯ T-DM1 has robust single-agent activity in patients with heavily pretreated, HER2-positive MBC and is well tolerated at the recommended phase II dose.