We performed a systematic review and meta-analysis on the response rates of 
patients with treatment-refractory urothelial carcinoma treated with programmed 
cell death 1 (PD-1) and programmed death ligand 1 (PD-L1) inhibitors. We 
reviewed the literature for prospective studies evaluating PD-1/PD-L1 inhibitors 
in refractory urothelial carcinoma patients, which formed the basis for US Food 
and Drug Administration approval of 5 different antagonistic antibodies 
targeting PD-1 or PD-L1 (atezolizumab, durvalumab, avelumab, nivolumab, and 
pembrolizumab). We considered studies examining PD-1/PD-L1-treated patients, 
which we identified using the following key terms in the Pubmed, Scopus, Web of 
Science, ClinicalTrial.gov, and Cochrane Library databases. Eligible studies 
had ≥ 20 patients each and reported response rates, duration of response, and 
overall survival (OS). We performed fixed and random-effects meta-analyses to 
model the point estimates for objective response rate and complete response. The 
median progression-free survival (PFS) and OS for studies reporting these 
statistics were evaluated. We found 10 eligible studies that met our inclusion 
criteria, providing extractable numerators and denominators for response rates, 
PFS, and OS for 1934 patients with metastatic urothelial carcinoma. The 
objective response rate was 18% (95% confidence interval, 15-22) for second-line 
or later therapies. The random-effects estimate for complete response was 4% 
(95% confidence interval, 3-5), including all disease locations and all PD-1 and 
PD-L1 inhibitors. Median OS and PFS were < 13 months and 3 months, respectively, 
across all studies, irrespective of PD-L1 expression. We found that the 
estimated response rates of agents included in this meta-analysis seem to be 
more favorable than other salvage therapies.