Antibodies Monoclonal/adverse effects/therapeutic use Antibodies Monoclonal Humanized/adverse effects/therapeutic use Antineoplastic Agents Immunological/*therapeutic use B7-H1 Antigen/*antagonists & inhibitors Clinical Trials Phase III as Topic Humans Network Meta-Analysis Programmed Cell Death 1 Receptor/*antagonists & inhibitors Salvage Therapy/*methods Survival Analysis Treatment Outcome Urinary Bladder Neoplasms/*drug therapy/*secondary PD-1 inhibitor PDL-1 inhibitor atezolizumab pembrolizumab urothelial bladder cancer