Upper tract urothelial carcinoma (UTUC) and urinary bladder cancer (UBC), though histologically similar, differ molecularly, prompting interest in their biomarker profiles for targeted therapies like antibody-drug conjugates (ADCs) enfortumab vedotin (targeting Nectin-4) and sacituzumab govitecan (targeting TROP-2). The gene discussed is TACSTD2; the disease is renal pelvis/ureter urothelial carcinoma.