Prognostic and clinicopathological value of PD-L1 in melanoma: a meta-analysis

Abstract Background There is a growing interest in using programmed death ligand-1 (PD-L1) as a prognostic marker for melanoma. We conducted this meta-analysis to explore the prognostic and clinicopathological value of PD-L1 in melanoma. Materials and Methods The electronic databases PubMed, Web of Science and the Cochrane Library were searched for relevant studies. The major investigated parameters were PD-L1 expression levels in relation to patient gender, tumor-infiltrating lymphocytes (TILs), tumor stage, lymph node (LN) metastasis, histological type, progression-free survival (PFS) and overall survival (OS). Odds ratios (ORs) and hazard ratios (HRs) were computed using the fixed-effect or random-effects model according to data heterogeneity. Results Positive PD-L1 expression was significantly associated with high levels of TILs (OR = 7.56, 95% CI 2.04-28.02), metastatic melanoma (OR = 0.45, 95% CI 0.30-0.67) and LN-positive melanoma (OR = 2.56, 95% CI 1.31-4.99) but not gender or histological type. In addition, the pooled HRs showed no relation between PD-L1 expression and PFS (HR = 1.18, 95% CI 0.83-1.69) or OS (HR = 0.77, 95% CI 0.47-1.25). When restricted to metastatic melanoma, positive PD-L1 expression was significantly related to prolonged OS (HR = 0.57, 95% CI 0.46-0.70). Conclusions Positive PD-L1 expression may be an important prognostic factor for longer OS in patients with metastatic melanoma.