A phase 1 study of weekly dosing of trastuzumab emtansine (T-DM1) in patients with advanced human epidermal growth factor 2-positive breast cancer.

Background: We conducted a phase 1, multicenter, open-label, dose-escalation study (TDM3569g) to assess the safety, tolerability, and pharmacokinetics of single-agent trastuzumab emtansine (T-DM1) administered weekly and once every 3 weeks in patients with HER2-positive metastatic breast cancer previously treated with trastuzumab. The weekly dose results are described here.

Methods: Patients were administered escalating doses of T-DM1 weekly, starting at 1.