According to presurgical stage, residual disease, her good performance status, participation in the phase III, randomized, placebo-controlled, double-blind clinical trial ASTEFANIA was proposed: this trial evaluated the efficacy and safety of adjuvant atezolizumab or placebo in combination with T-DM1 for HER2-positive breast cancer at high risk of recurrence following preoperative therapy. This evidence concerns the gene ERBB2 and breast cancer.