According to the National Comprehensive Cancer Network (NCCN) guidelines for the treatment of ovarian cancer (version 2024), trastuzumab deruxtecan (T-DXd), a human epidermal growth factor 2 (HER2)-directed ADC, is approved to treat PROC patients with HER2 IHC 3+/2+ expression. The gene discussed is ERBB2; the disease is ovarian carcinoma.