Abstract: Objective: To assess the efficacy and safety of sintilimab,an immune checkpoint inhibitor independently developed in China,in combination with chemotherapy for the treatment of advanced non-small cell lung cancer (NSCLC),and to explore the serological indicators that may serve as predictors for the response to the combined regimen,thereby providing a reference for the clinical treatment of NSCLC. Methods: The clinical data of 160 patients with advanced NSCLC was retrospectively analyzed.According to the regimens,patients were divided into the control group and the observation group,with 80 cases in each group.Patients in the control group received platinum-containing two-drug chemotherapeutic regimen,while patients in the observation group received sintilimab plus chemotherapy.After 4 treatment cycles,the therapeutic efficacy,the occurrence of adverse reactions and the changes in the levels of serum tumor markers,in the two groups were observed,and the relationship between serology indicators and therapeutic efficacy was analyzed. Results: The observation group and the control group exhibited 43.8% (35/80) and 28.8% (23/80) in the objective response rate,and 85.0% (68/80) and 68.8% (55/80) in the disease control rate,respectively,and the differences of which were statistically significant (P<0.05).While the differences in levels of serum tumor marker before and after the treatment in each group were statistically significant (P<0.05 to P<0.01),while the differences between the two groups before and after treatment were not statistically significant (P>0.05).Most of the adverse reactions that occurred were grade 1-2,and no grade 5 adverse reaction event occurred.No event of medication discontinuation due to the occurrence of adverse reactions was observed.The differences in the overall occurrence of adverse reactions between the groups were not statistically significant (P>0.05).Multivariate logistic regression analyses showed that the pre-treatment neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio were independent factors influencing the efficacy of patients treated with sintilimab combined with chemotherapy. Conclusions: Regimen of sintilimab in combination with platinum-containing dual-agent chemotherapy demonstrates superior efficacy compared to platinum-containing dual-agent chemotherapy alone.Adverse effects are similar between the two groups,however,specific events such as hyperthyroidism can be observed in the combination regimen.Additionally,the pre-treatment neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio may have the potential in predicting the efficacy of regimen of sintilimab combined with chemotherapy.