Summary
This study will evaluate the efficacy, safety and patient-reported outcomes of
trastuzumab emtansine plus atezolizumab compared with trastuzumab emtansine plus placebo
in participants with HER2-positive and PD-L1-positive LABC or MBC.Participants must have
progressed either during or after prior trastuzumab- (+/- pertuzumab) and taxane-based
therapy for LABC/MBC; or during (or within 6 months after completing) trastuzumab-
(+/-pertuzumab) and taxane-based therapy in the neoadjuvant and/or adjuvant setting.