1911PAnalysis of gut microbiota in advanced non-small cell lung cancer (NSCLC) patients treated with immune-checkpoints blockers

Abstract Background The microbiota community is considered as an organ of the human body. Recent studies have found that dysbiosis may have an impact on the interaction between immune regulation and tumor treatment. The main objective of this study is to characterize the gut microbiota in patients with non-small cell lung cancer (NSCLC) in advanced stages, and its relationship with obesity, smoking habits, clinical pathological features and response to treatment with immune-checkpoints blockers (ICB). Methods 16S rRNA gene sequencing was performed on 48 stool samples from advanced NSCLC patients prior to treatment with ICB (PD-1 inhibitor and PD-L1 inhibitor). The database used for the taxonomic assignation was the SILVA_release_132. The parametric statistical analysis was performed in SPSS package (15.0). A p-value Results The average age of the 48 patients was (64±10 years), of which 36 patients were male, 27 patients present PD-L1 positive, 28 patients with smoking habits. 261 different genus were detected in all the samples, being Bacteroides 28.11%, Alistipes 6.58% and Prevotella 4.67% the more frequently found. Non-smokers presented significantly higher richness and diversity (Chao1 p = 0.001, Shannon p = 0.001, Simpson p = 0.03) compared with current and former smokers. Greater abundance of genus Blautia was associated with obesity (p = 0.043). In addition, according to histology, greater abundance of genus Odoribacter was observed in squamous cell carcinoma patients compared to adenocarcinoma (p = 0.04); and regarding stage, stage IIIB patients presented higher proportion of genus Lactobacillus than stage IV (p = 0.017).Patients with progression disease to the ICB treatment presented significantly higher abundance of genus Ruminococcaceae_UCG-013 (p = 0.019). Conclusions We have been demonstrated a potential relationship between the gut microbiota in NSCLC patients and clinical-pathological features, which requires confirmation in a larger study. The more relationship with the ICB is under evaluation and will be presented at the meeting. Funded by CB16/12/00350 from CIBEROnc, PI18/00226, and PI15-00753 from ISCIII. Legal entity responsible for the study Fundacion Investigacion Hospital General Universitario Valencia. Funding CIBEROnc, Instituto de Salud Carlos III. Disclosure All authors have declared no conflicts of interest.