Daniels B, Kiely BE, Tang M, et al. - Researchers conducted this retrospective, whole-of-population cohort analysis to determine the treatment patterns as well as overall survival (OS) results in patients receiving treatment with trastuzumab emtansine (T-DM1) for HER2-positive metastatic breast cancer (HER2+MBC) in routine clinical care. Persons starting T-DM1 for HER2+MBC between October 2015 and May 2019 in Australia, were included. Experts herein benchmarked results to those noted in the pivotal, EMILIA trial. Initiation of T-DM1 in 345 patients was documented: 309 as second-line therapy for HER2+MBC and 36 as first-line treatment. Receipt of endocrine therapy in 51% of patients, and receipt of pertuzumab before initiating T-DM1 was seen in 98% of second-line patients. Findings underscore that disparities existed in patient features (older, more previous pertuzumab therapy) as well as in outcomes (shorter OS) from the T-DM1 pivotal trial. This work offers real-world estimates to inform patient, clinician and policy, decisions regarding the employment of HER2-targeted therapies in routine clinical care.