Sacituzumab govitecan (SG), an antibody-drug conjugate (ADC) that targets Trop2, has gained US Food and Drug Administration (FDA) approval for use in treating metastatic triple-negative breast cancer (TNBC), hormone receptor–positive breast cancer (HR+ BC), and metastatic urothelial carcinoma (5, 8). The gene discussed is TACSTD2; the disease is breast cancer.