By understanding tumor immunology in UC, immune checkpoint inhibitors, targeting on programmed death 1 (PD-1) and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) pathways, had been proven as first-line treatment for cisplatin-ineligible metastatic UC and as second-line treatment for patients with platinum-refractory metastatic UC by the U.S Food and Drug Administration (FDA). Here, CTLA4 is linked to neoplasm.