ERBB2 and breast cancer: On the basis of the results of this trial, a randomized phase III trial (ClinicalTrials.gov Identifier: NCT04873362; Table 1) is now being conducted to evaluate T-DM1 ± atezolizumab in PD-L1 overexpressing breast cancers with residual invasive Her-2/neu-positive breast cancer following neoadjuvant taxane-based and Her-2/neu-targeted therapy.