This work provided the preclinical foundation for the HERMIONE clinical trial (NCT02213744) in anthracycline-naïve patients with locally advanced/metastatic HER2-positive breast cancer patients receiving MM-302 plus TZM versus the chemotherapy of physician’s choice (GEM, capecitabine, or vinorelbine) plus TZM. The gene discussed is ERBB2; the disease is breast carcinoma.