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

Background: The predictive role of exosomal programmed cell death ligand l (exoPD-L1) in prognosis has been studied extensively; however, there is still no consensus.
Methods: Three 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.
Results: 15 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).
Conclusion: Circulating 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.
(© 2024. The Author(s), under exclusive licence to Federación de Sociedades Españolas de Oncología (FESEO).)