In addition to the results from the APT trial, preliminary findings from a randomized phase II study of adjuvant ado-trastuzumab emtansine (TDM-1) vs. trastuzumab + paclitaxel in patients with stage I HER2+ BC showed excellent local-regional control with only 2 LRR events out of 383 patients in the TDM-1 group and 4 LRR events in the 114 patients treated with paclitaxel-trastuzmab26. This evidence concerns the gene ERBB2 and breast cancer.