Correlation between exosomal PD-L1 and prognosis in patients with cancer: a systematic review and meta-analysis

BackgroundThe predictive role of exosomal programmed cell death ligand l (exoPD-L1) in prognosis has been studied extensively; however, there is still no consensus.MethodsThree databases, including EMBASE, PubMed, and Web of Science, were searched through January 4, 2024. The pooled hazard ratios (HRs) with 95% confidence intervals (95%CIs) were used to identify the relationship between circulating exoPD-L1 and prognosis.Results15 studies with 1091 patients with cancer were included in this statistical analysis. High exoPD-L1 level was correlated with shorter progression-free survival (PFS) (HR = 2.58, 95% CI: 1.75-3.81) and overall survival (OS) (HR = 1.61, 95% CI: 1.32-1.98). Meanwhile, we found that dynamic upregulation of circulating exoPD-L1 in the early stages of immunotherapy was a favorable factor for prognosis (PFS: HR = 0.34, 95% CI: 0.23-0.51; OS: HR = 0.21, 95% CI: 0.13-0.26).ConclusionCirculating exoPD-L1 may be a valuable prognostic indicator for patients with cancer and monitoring its changes in the early stages of immunotherapy might be used to predict tumor response and clinical outcome. This conclusion may not apply to superficial tumors.