Clinical Analysis Of PD-L1 Expression In Lung Cancer Patients Without Driver Gene Mutations

Background and aims:PD-1/PD-L1 inhibitors play an important role in the first-line and second-line treatment of non-small cell lung cancer(NSCLC),indicating a new therapy strategy of NSCLC.PD-L1 protein is an effective way to predict immunotherapy response.In this study,we analysed PD-L1 expression in advanced lung cancer patients without driver gene mutations,and explored the clinicopathologic features and radiographic characteristics in patients with PD-L1 expression for efficient selection of potential detection population.Moreover,the effects of PD-L1 expression on efficacy and prognosis of patients treated with chemotherapy were investigated in the real world.Methods:In this study,locally advanced or metastatic NSCLC patients diagnosed in the first affiliated hospital of Zhejiang University from November 2017 to October 2019 were included.EGFR mutation and ALK rearrangement were negative,and PD-L1 was detected with Ventana SP263 or Dako 22C3.The cut-off was defined as 1%.In this study,clinicopathologic features and radiographic characteristics of patients with PD-L1 expression were analysed,and multi-factor analysis was used to explore the independent predictors of PD-L1 expression.The efficacy of PD-L1 positive group and the negative group receiving platinum-based chemotherapy was compared.We compared survival time between the two groups with Kaplan-Meier method.Results:Among the 51 lung cancer patients without driver gene mutations,25(49.0%)patients showed positive results,and 2(3.9%)patients showed high expression.PD-L1 positive results were more common in patients with younger age(p=0.032)and low differentiation(p=0.036),while negative results were more common in patients with multiple organ metastases(≥2 organs)(p=0.030).PD-L1 expression was not associated with inflammatory markers,tumor related markers,specimen type,lesion type or chest CT findings.Compared to the negative group,the positive group had higher SUVmax(12.70±3.02 vs 8.58±3.89,p=0.028).ROC curve analysis showed that the area under curve was 0.833(95% CI: 0.600-1.067,p=0.027).The optimal cut-off of SUVmax was 9.95,and the corresponding sensitivity and specificity were 0.83,0.91.Logistic regression analysis showed that differentiation degree(OR: 4.954,95% CI: 1.201-20.432,p=0.027)and the number of metastatic organs(OR: 0.079,95% CI: 0.010-0.606,p=0.015)were independent predictive factors of PD-L1 expression.In the patients receiving platinum-based chemotherapy,the objective response rate(ORR)of the positive group and the negative group was 33.3%,41.7%,respectively.The PD-L1 positive group was related with a significantly shorter progression-free survival(PFS)(m PFS: 3.5 months vs 5.6 months,p=0.030),but there was no significant correlation between PD-L1 expression and overall survival(OS)(p=0.916).Conclusion:The retrospective study showed that low differentiation was significantly correlated with increased PD-L1 expression,while multiple organ metastases(≥2 organs)were negatively correlated with PD-L1 expression.Higher SUVmax value was more common in PD-L1 positive group.When the SUVmax was >9.95,the positive expression probability of PD-L1 was high.In patients receiving chemotherapy,PD-L1 positive result was associated with worse PFS,but there was no significant association with ORR and OS.