Personalized cancer therapy is becoming more histology agnostic as treatments are chosen based on tumor genomics rather than tumor type.1,2 Human epidermal growth factor receptor 2 (HER2) is a transmembrane tyrosine kinase receptor that belongs to the epidermal growth factor receptor family and is encoded by the ERBB2 (HER2) gene (chromosome 17q12). The gene discussed is ERBB2; the disease is cancer.