In a multicenter retrospective study involving 27 UC patients with HER2-negative or low HER2 expression—including 20 cases of UTUC—partial responses (PR) were achieved in 8 patients (30.8%), while 12 patients (46.2%) exhibited stable disease (SD), resulting in an objective response rate (ORR) of 30.8% and a disease control rate (DCR) of 76.9%. The gene discussed is ERBB2; the disease is renal pelvis/ureter urothelial carcinoma.