MA04.09 Study of Exosomes in NSCLC for Biomarkers Searching

Abstract

Background: Lung adenocarcinoma (LUAD) accounts for 40% of all lung cancer cases. Although driver mutations in the K-RAS oncogene occurs in 25% of all LUAD cases, to date, there are no available targeted therapies. Infiltrating neutrophils in LUAD are indicative of the worst survival outcomes. The C-X-C motif chemokine receptor 2 (CXCR2) mediates their recruitment to the tumour microenvironment where they promote a pro-tumorigenic environment. CXCR2 ligand expression is higher in KRAS-driven LUAD compared to the other most frequently mutated oncogenes. Therefore, we hypothesize that K-RASdriven LUAD may be the best candidate for a CXCR2 targeted treatment strategy. Method: The PREdiction of Clinical Outcomes from Genomic Profiles (PRECOG) is a dataset of gene expression and survival outcome. The dataset includes data from approximately 18 000 human patients with 39 different malignancies. The dataset was used to determine whether high neutrophil infiltration, CXCR2 expression and CXCR2 ligand expression were associated with poor survival outcomes in LUAD. A 100 patient LUAD tissue microarray was built and stained for neutrophil elastase and CXCR2 by immunohistochemistry. Kaplan-Meier curves were used determine the effect of high neutrophil or CXCR2+ cell infiltration in the LUAD tumour microenvironment on survival outcome. The Cancer Cell Line Encyclopedia (CCLE) is an online dataset that provides gene expression and genotype data from 947 human cancer cell lines (36 cancer types). Expression data of all LUAD cell lines (n¼70) from CCLE was obtained for all known CXCR2 ligands. The expression of CXCR2 ligands in K-RAS, EGFR, ALK and ROS-1-driven LUAD cell lines was compared. Microfluidics devices were used to compare the neutrophil recruitment to K-RAS, EGFR, ALK and ROS-1-driven LUAD cell lines. The neutrophil recruitment to each of the cell lines was compared in the presence and absence of CXCR2 inhibition. Result: Using the PRECOG dataset, we found that CXCR2 expression in neutrophils is at least 18-fold greater than its expression in other immune cell types. Using all the LUAD cell lines (n¼70) available on the CCLE, we found that K-RAS-driven LUAD is the highest CXCR2 ligand expresser as compared to EGFR, ALK and ROS1-driven LUAD. Moreover, using PRECOG, we found that poorer survival outcome is associated with high expression of eight out of nine known CXCR2 ligands (p <0.05). In addition, high neutrophil infiltration in LUAD is associated with the worst survival outcome compared to other immune cell infiltrates (p <0.001). In accordance with the PRECOG data, the presence of infiltrating neutrophils in a 100 patient LUAD tissue microarray is associated with poorer survival outcome when compared to patients with no infiltrating neutrophils (p <0.05). Neutrophil migration to K-RAS, EGFR, ALK and ROS1-driven LUAD cell lines was examined in microfluidics devices and found to be highest in K-RAS-driven LUAD. CXCR2 inhibition reduced neutrophil migration only in K-RAS-driven lung adenocarcinoma (p <0.05). Conclusi...