<h4>Background</h4>The management of human epidermal growth factor receptor 2 (HER2)-mutant non-small cell lung cancer (NSCLC) remains a significant clinical challenge, with limited effective and accessible treatment options beyond antibody-drug conjugates such as trastuzumab deruxtecan (T-DXd). The gene discussed is ERBB2; the disease is non-small cell lung carcinoma.