Association Between PD-L1 Expression Between And Driver Gene Status In Non-small Cell Lung Cancer:A Meta-analysis

Background:Interaction of programmed cell death 1(PD-1)receptor interacting with programmed cell death 1 ligand 1(PD-L1)is an important mechanism of immune escape in non-small-cell lung cancer(NSCLC).Thus,blockade of PD-1/PD-L1 becomes a novel target for immunotherapy in recent years.There is an urgent need to recognize patients who would deserve the clinical benefit of these emerging therapies.The expression level of PD-L1 is considered to a biomarker of better immunotherapy outcomes,while mutation of EGFR/ALK is tightly associated with poor immunotherapy outcomes.Nowadays,the association between PD-L1 expression and driver gene status remains controversial.Objective:To further assess the association between PD-L1 expression and driver gene status in patients suffering NSCLC.Method:We performed a meta-analysis of 28 studies(includes 7646 patients)which were published before January,2018.Pooled odds ratios(ORs)with 95%confidence intervals(CI)were used to describe the correlation.Subgroup analysis was performed based on the regions of study,histology and cutoff levels.Results:A lower frequency of PD-L1 positivity was observed in NSCLCs harboring EGFR mutation(OR=0.62,95%CI:0.44-0.88,p=0.008).No significant differences in PD-L1 expression were observed among patients with different ALK,BRAF,HER2,PIK3CA status and c-Met expression level.Higher level of PD-L1 was found in tumors with KRAS mutation(OR=1.48,95%CI:1.20-1.82,p=0.000).PD-L1 expression level was not significantly different between triple(EGFR/ALK/KRAS)wild type NSCLCs and those with EGFR/ALK/KRAS mutation.Conclusion:PD-L1 expression in EGFR mutated NSCLCs were lower than those in EGFR wild type NSCLCs,while tumors with KRAS mutation showed higher levels of PD-L1.No evidences suggest PD-L1 expression is associated with ALK,BRAF,c-Met expression,HER2 or PIK3CA status.