Significance of PD-L1 in Metastatic Urothelial Carcinoma Treated With Immune Checkpoint Inhibitors: A Systematic Review and Meta-Analysis

Immune checkpoint inhibitors (ICIs) have broadened the metastatic urothelial carcinoma (mUC) therapeutic scenario. The association of programmed death ligand 1 (PD-L1) with response and survival in patients treated with ICIs is still controversial. To evaluate the association of PD-L1 with response rate and overall survival among patients with mUC treated with ICIs. PubMed, Embase, American Society of Clinical Oncology and European Society for Medical Oncology Meeting Libraries, and Web of Science were searched up to December 10, 2023. Two authors independently screened the studies. Included studies were randomized and nonrandomized clinical trials enrolling patients with mUC receiving ICIs with available overall survival (OS), progression-free survival (PFS), or overall response rate (ORR) data, separated between patients with PD-L1-positive and -negative tumors. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline was followed. Two reviewers independently extracted data. Fixed- or random-effects models were used depending on the heterogeneity among the studies. Primary outcomes were odds ratios (ORs) for ORR and hazard ratios (HRs) for OS, comparing patients with PD-L1-positive tumors and patients with PD-L1-negative tumors. Secondary outcomes were the PFS HR between patients with PD-L1-positive and -negative tumors and OS HR between ICI arms and non-ICI arms of only randomized clinical trials. A total of 14 studies were selected, comprising 5271 patients treated with ICIs (2625 patients had PD-L1-positive tumors). The ORR was 13.8% to 78.6% in patients with PD-L1-positive tumors and 5.1% to 63.2% in patients with PD-L1-negative tumors, with an association between PD-L1 status and ORR favoring patients with PD-L1-positive tumors (OR, 1.94; 95% CI, 1.47-2.56; P