In the KRISTINE trial, patients who experienced pCR after neoadjuvant T-DM1 plus P had 96.7% 3-year invasive DFS (despite only 9.1% receiving adjuvant chemotherapy), and the I-SPY2 trial reported a 93–97% 3-year event-free survival for patients with pCR following varied neoadjuvant regimens for stage II–III HER2+ breast cancer, including investigational regimens7,8. This evidence concerns the gene ERBB2 and breast carcinoma.