PD-L1 and gastric cancer prognosis: A systematic review and meta-analysis

<div><p>The expression of Programmed cell Death Ligand 1 (PD-L1) is observed in many malignant tumors and is associated with poor prognosis including Gastric Cancer (GC). The relationship between PD-L1 expression and prognosis, however, is controversial in GC. This paper purports to use a meta-analysis to investigate the relationship between PD-L1 expression and prognosis in GC. For this study, the following databases were searched for articles published from June 2003 until February 2017: PubMed, EBSCO, Web of Science and Cochrane Library. The baseline information extracted were: authors, year of publication, country where the study was performed, study design, sample size, follow-up time, baseline characteristics of the study population, pathologic data, overall survival (OS). A total of 15 eligible studies covering 3291 patients were selected for a meta-analysis based on specified inclusion and exclusion criteria. The analysis showed that the expression level of PD-L1 was associated with the overall survival in GC (Hazard Ratio, HR = 1.46, 95%CI = 1.08–1.98, P = 0.01, random-effect). In addition to the above, subgroup analysis showed that GC patients with deeper tumor infiltration, positive lymph-node metastasis, positive venous invasion, Epstein-Barr virus infection positive (EBV+), Microsatellite Instability (MSI) are more likely to expression PD-L1. The results of this meta-analysis suggest that GC patients, specifically EBV+ and MSI, may be prime candidates for PD-1 directed therapy. These findings support anti-PD-L1/PD-1 antibodies as a kind of immunotherapy which is promising for GC.</p></div

Begg’s and Egger’s funnel plot with 95% CI for OS publication bias testing.

<p>Begg’s and Egger’s funnel plot with 95% CI for OS publication bias testing.</p

Characteristics of studies included in the meta-analysis.

<p>Characteristics of studies included in the meta-analysis.</p

Exploratory subgrouping analysis of heterogeneity.

<p>Exploratory subgrouping analysis of heterogeneity.</p

Correlation of PD-L1 expression with clinicopathological characteristics and Begg’s and Egger’s test in subgroup analysis.

<p>Correlation of PD-L1 expression with clinicopathological characteristics and Begg’s and Egger’s test in subgroup analysis.</p

Flow chart of study selection.

<p>Flow chart of study selection.</p

Forest plot describing the association between PD-L1 positive and HR of patients with GC.

<p>Forest plot describing the association between PD-L1 positive and HR of patients with GC.</p