The KATHERINE trial (NCT01772472) was a phase 3 trial for patients with HER2-positive breast cancer and residual disease in the breast and in the axilla or not after NAC with a taxane (with or without an anthracycline) and trastuzumab (Table 1), comparing efficacy of adjuvant T-DM1 versus trastuzumab58. This evidence concerns the gene ERBB2 and breast carcinoma.