Association of <i>ERBB2</i> Copy Number and Gene Coalterations With Trastuzumab Efficacy and Resistance in Human Epidermal Growth Factor Receptor 2–Positive Esophagogastric and Gastric Cancer

Abstract

<i>ERBB2</i> CN and gene coamplification in the HER2 signaling pathway were positive and negative predictors of PFS in trastuzumab-treated HER2-positive AGC patients, respectively. HER2-positive AGC patients with a high VAF of <i>ERBB2</i> showed poor outcomes and may need HER2 tyrosine kinase inhibitors and trastuzumab deruxtecan.