Trastuzumab, also called fam-trastuzumab deruxtecan-nxki in the USA or T-DXd, is an antibody-drug conjugate that targets HER2 specifically (https://www.fda.gov/news-events/press-announcements/fda-approves-new-treatment-option-patients-her2-positive-breast-cancer-who-have-progressed-available). The gene discussed is ERBB2; the disease is breast cancer.