Prognostic value of programmed death-ligand 1 in solid tumors: A meta-analysis.

Abstract

e19121 Background: The programmed cell death 1 (PD-1)/programmed cell death 1 ligand 1 (PD-L1) pathway plays a crucial role in cancer immuno-surveillance and is the target of approved immunotherapeutic drugs. Available data suggest a variable prognostic impact of PD-L1 expression in solid tumors. Methods: A systematic literature search of electronic databases identified publications exploring the effect of PD-L1 on overall survival (OS) and/or progression-free survival (PFS). Hazard ratios (HR) were pooled in a meta-analysis using generic inverse-variance and random effects modeling. Subgroup analyses were conducted based on disease site, stage of disease, and method of PD-L1 quantification using the Deeks method. Results: One hundred eighty-eight studies comprised of 212,748 patients met the inclusion criteria. PD-L1 expression was associated with worse OS (HR 1.32, 95% confidence interval (CI) 1.25 - 1.38; P < 0.001). There was significant heterogeneity between disease sites (subgroup P = 0.002) with pancreatic, hepatocellular and genitourinary cancers being associated with the highest magnitude of adverse outcome (Table). PD-L1 was also associated with worse overall PFS (HR 1.19, 95% CI 1.09 - 1.30; P < 0.001). Stage of disease did not significantly affect the results (subgroup P = 0.52), nor did the method of quantification (immunohistochemistry or mRNA) (subgroup P = 0.70). Conclusions: High expression of PD-L1 is associated with worse cancer outcomes albeit with significant heterogeneity between disease sites. The effect seems consistent in early stage and metastatic disease and is not sensitive to method of PD-L1 quantification. [Table: see text]