Platelet-to-lymphocyte ratio for prognostication in immune checkpoint inhibitor-treated cancer patients: a meta-analysis of 13027 patients highlighting nivolumab-responsive renal cell carcinoma

Objective: To assess platelet-to-lymphocyte ratio (PLR) prognostic utility for overall (OS) and progression-free survival (PFS) in immune checkpoint inhibitor-treated cancer patients, and examine impacts of geography, cancer type, cutoff, ICI class, treatment line and stage. Methods: A systematic literature search identified studies investigating PLR and prognosis in ICI treated patients. Hazard ratios (HRs) with 95% confidence intervals (CIs) were pooled using random-effects models. Subgroup analyses examined key covariates; publication bias was assessed. Results: Analysis of 98 publications (86 OS, 72 PFS) demonstrated that elevated PLR was a robust predictor of shorter OS (HR 1.79, 95% CI: 1.60-2.00) and PFS (HR 1.60, 95% CI: 1.44-1.78). Subgroup analyses revealed: (1) Geographic region: Asian populations exhibited the most consistent correlation with OS and the highest PFS risk (69%). (2) Cancer type: For OS, prognostic value was maintained across all cancers; the most pronounced impacts were observed in hepatocellular carcinoma (HR 2.10), esophageal carcinoma (HR 2.08), and head and neck squamous cell carcinoma (HR 2.61). For PFS, a notable link to poor outcomes was observed in NSCLC and hepatocellular carcinoma, whereas renal cell carcinoma showed no such correlation. (3) PLR cutoff: both PLR ≥180 (OS: HR 1.87; PFS: HR 1.68) and PLR