Prognostic value and clinicopathological characteristics of PD-L1 overexpression in non-Hodgkin lymphoma: a meta-analysis

BACKGROUND: Programmed cell death ligand 1 (PD-L1) has already been detected in various carcinomas. In non-Hodgkin lymphoma (NHL), however, the prognostic value of PD-L1 overexpression remains unclear. METHODS: A meta-analysis of 2321 NHL patients from 12 studies was performed. Hazard ratios (HRs) with 95% confidence intervals (CIs) were used to evaluate the correlation between PD-L1 overexpression and prognosis of NHL, and odds ratios (ORs) with 95% CIs were used to assess the association of PD-L1 overexpression with clinicopathological factors. RESULTS: The results showed that no significant difference between PD-L1 positive and negative groups was detected in NHL (HR: 1.40, 95% CI: 0.90–2.19; P = 0.137). Nevertheless, the results indicated that PD-L1 overexpression was associated with poor prognosis in the subtype of diffuse large B cell lymphoma (DLBCL) (HR: 1.70, 95% CI: 1.05–2.74; P = 0.031). We also performed subgroup analyses and meta-regression. The pooled OR showed that PD-L1 overexpression was associated with B symptoms, higher international prognostic index (IPI) score (3, 4, and 5 points) and Ann Arbor Stages III and IV. CONCLUSIONS: The meta-analysis demonstrated that PD-L1 expression was not associated with prognosis of NHL but was associated with prognosis of DLBCL.