The efficacy and safety of PD-1/PD-L1 immune checkpoint inhibitors in treating advanced urothelial cancer: a meta-analysis of clinical trials

Survival outcomes in advanced urothelial cancer (UC) are dismal. Over the past years, immunotherapy remains an evolving treatment modality for these patients. This meta-analysis was performed to comprehensively evaluate the efficacy and safety of immune checkpoint inhibitors. For this purpose, 18 clinical trials comprising a total of 3,144 patients were identified from the PubMed database up to September 2020. Overall, the objective response rate (ORR) to PD-1/PD-L1 inhibitors was 0.20 [95% confidence intervals (CI) 0.17–0.23]. Furthermore, the pooled 1-year overall survival (OS) and 1-year progression-free survival (PFS) rates were 0.43 (95% CI 0.33–0.53) and 0.19 (95% CI 0.17–0.21), respectively. The summary rates of any-grade and grade ≥3 adverse events (AEs) were 0.66 (95% CI 0.58–0.74) and 0.13 (95% CI 0.09–0.18), respectively. Among the different subgroups, PD-1/PD-L1 inhibitors elicited a promising ORR in patients with lymph node-only metastasis compared to those with visceral metastasis (0.41 VS. 0.17). Additionally, patients with primary tumor in the lower tract had higher ORR compared to those with primary tumor in the upper tract (0.24 VS. 0.15). Briefly speaking, this immunotherapy protocol showed an encouraging efficacy and acceptable safety profile in the treatment of advanced UC. Moreover, our findings provided potential clinical significance for patients with lymph node-only metastasis or primary tumor in the lower tract. However, these exciting findings need further confirmation.