MA05.03 Differential Frequency of Blood Immune Cells as Biomarkers for Risks Assessment in bioMILD Lung Cancer Screening Trial

Abstract

The role of adaptive and innate systemic immunity in lung carcinogenesis is poorly understood both in murine and clinical settings. Nevertheless, studying peripheral blood immune cells could provide insights into the pathogenesis of this process and allow the identification of novel biomarkers for early diagnosis and intervention. In line with this hypothesis is our previous finding that circulating microRNAs deriving from peripheral immune cells compose a three level miRNA signature risk Classifier (high, intermediate, low MSC) able to predict cancer development in heavy smokers. In this study we aimed to test whether differential frequencies of specific immune cell subsets in the peripheral blood of subjects enrolled in the bioMILD screening trial could help identifying high risk subjects and implement the accuracy of the MSC test. Methods: Peripheral blood mononuclear cells (PBMC) prospectively isolated and stored from blood of volunteers enrolled in the bioMILD screening trial were analyzed by multiparametric flow cytometry (Cytoflex) using a total of 23 antibodies specific for markers encompassing monocyte and myeloid-derived suppressor cells (MDSC) subsets, regulatory T cells, cytolytic NK cells and activated/exhausted/ hyperexausted T cells. To maximize the chances of detecting differential phenotypic patterns, the analysis was initially performed in a first training set of samples of the bioMILD trial including 20 Low Dose Computed Tomography (LDCT)-detected lung cancers and 20 matched cancer-free heavy smokers controls. Data were then validated in PBMC from 80 LDCT-detected lung cancer patients and 80 matched (1:1) cancer-free controls of the bioMILD trial. The C-reactive protein (CRP) plasma level was also measured in all subjects as inflammation marker. An increase of pro-angiogenic monocytes (CD14+CX3CR1+) and monocytic-MDSC (M-MDSC, CD14+HLA-DRneg) was observed in the patients group compared to controls. Conversely, intermediate monocytes (CD14+CD16+), which are associated with cancer immunosurveillance, and activated cytotoxic T (CD3+CD8+PD-1+) were instead reduced in lung cancer patients compared to controls. The plasma level of CRP did not differ in cases vs controls and showed no correlation with any of the analyzed immune cell subpopulations.The majority of these cell subsets were able to discriminate patients and controls independently from MSC risk level. However, specific cell subsets were differentially expressed in MSC high compared to low/intermediate risk patients. Among them, hyper-exhausted T cells (CD3+CD8+PD-1+LAG3+) and M-MDSC were increased in MSC high risk patients, while CD16highCD56+CD3+ NKT cells, protective elements mediating antibody-dependent cell cytotoxicity, were instead reduced. Conclusion: Altogether, these findings suggest that MSC risk might associate with a immunosuppressed systemic immunity that could predispose to lung carcinogenesis. Hence, the characterization of the peripheral myeloid/lymphoid compartments can help distinguishing lung cancer screening cases and controls and may thus implement the accuracy of the blood miRNA-based MSC test. immune cells, biomarkers, screening