Indeed, we identified more than one third of patients with HER2-0 phenotype at baseline showing a conversion to HER2-low-positive expression after neoadjuvant treatment, thus suggesting that the evaluation of HER2 expression on residual disease may allow the access to potentially effective novel treatment strategies in a not negligible proportion of patients who would otherwise be excluded based on the primary tumor phenotype. The gene discussed is ERBB2; the disease is neoplasm.