An Open-Label, Multi-Center Phase I/II Study of the Safety and Tolerability of the Combination of Trastuzumab-MCC-DM1 (T-DM1) With Docetaxel, and Potentially Pertuzumab, for Treatment for Patients With Advanced Breast Cancer

This is an open-label, multi-center, non-randomized study of the safety and tolerability of the combination of T-DM1 plus docetaxel for the treatment of participants with metastatic breast cancer (MBC) and of T-DM1 plus docetaxel with or without pertuzumab, for the treatment of participants with locally advanced breast cancer (LABC). The study comprises an initial dose finding (feasibility) part to determine the maximum tolerated dose (MTD) of T-DM1 and docetaxel, followed by an extension part aiming to consolidate the safety and efficacy of the recommended docetaxel/T-DM1 combination regimen.