Efficacy and safety of programmed cell death-1/programmed cell death ligand-1 inhibitors in advanced urothelial malignancy: A systematic review and meta-analysis

INTRODUCTION: Programmed cell death-1/programmed cell death ligand-1 (PD-1/PDL-1) inhibitors are the newest class of approved drugs for advanced urothelial cancer (AdUC). This review aims to collate the evidence for their efficacy and safety in various treatment settings. METHODS: Extensive search of databases was performed (updated May 2018) and the protocol was registered on PROSPERO (CRD42017081568). The review was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analysis statement. STATA (v 12) and Revman 5.3.5 were used for data analysis. RESULTS: Ten nonrandomized, open-label clinical trials were included in this review. PD-1/PD-L1 inhibitors were used as second-line, stand-alone in eight trials and as first-line in cisplatin-ineligible in two trials. Heterogeneity was observed for study design, PDL-1 testing methods, cutoff criterias used and translational markers evaluated. The pooled objective response rate (ORR) was 18.2% (95% confidence interval [CI] 15.1–21.2, n = 1785) with PD-1/PDL-1 inhibitors in second-line settings as compared to 12.6% (95% CI 10.3–14.9, n = 736) with second-line chemotherapy and 23.7% (95% CI 19.9–27.4, n = 489) with PD-1/PDL-1 inhibitors as first-line therapy in cisplatin-ineligible patients. The median progression-free survival and overall survival was similar with PD-1/PD-L1 inhibitors in both second- and first-line treatment settings (1.5–2.9 vs. 2.0–2.7 months and 7.9–18.2 vs. 15.9 months) and second-line chemotherapy (3.3–4.0 months and 7.4–8 months). Odds of achieving ORR was 0.10 (95% CI 0.03–0.31, n = 229) in the second-line, stand-alone setting with a combined positive score (CPS) cutoff of 25% and was 0.34 (95% CI 0.19–0.62, n = 265) with a CPS cut-off of 10% in first-line setting in the cisplatin-ineligible. CONCLUSIONS: PD-1/PDL-1 inhibitors appear to be promising in the treatment of AdUC and CPS may be a potentially reliable biomarker for predicting response but needs validation. Caution needs to be exercised until more data are available on imAEs and further studies are required to prove their worth as the standard of care.