Abstract 3377: Immunosuppressive features characterize tumor tissues and peripheral blood of lung cancer patients
Authors: Boeri Mattia , Huber Veronica , Fortunato Orazio , Pastorino Ugo , Rivoltini Licia , Sozzi Gabriella 
Published: June 2022

The role of immunity at the local and peripheral level is a recognized hallmark of cancer. The immunosuppressive and inflammatory background of lung cancer (LC), led us to hypothesize that the tumour and the circulating immune cell profiles could be source of biomarkers for LC risk assessment. In this respect we already developed a plasma microRNA-signature classifier (MSC) that stratifies LC screening patients in high, intermediate and low risk groups. To get insight we investigated tumour tissues and peripheral blood immune cell profiles of these patients. The possibility to develop molecular tests reflecting an immunosuppressive status for prognostic and diagnostic purposes was also explored.

The immune cell composition of 40 frozen LC tissues collected during screening trials from patients with a different MSC risk profile were assessed by deconvolution analysis using CIBERSORT software. Results were validated by RT-qPCR and IHC, as well as using RNAseq data from the 1000 lung cancer patients of The Cancer Genome Atlas (TCGA) database. From a training set composed by 20 LC patients and 20 matched controls, we analyzed peripheral blood mononuclear cells (PBMCs) by flow cytometry using a 24 marker panel to encompass monocyte and myeloid-derived suppressor cells (MDSC) subsets, regulatory T cells, cytolytic NK cells and activated/exhausted/hyperexausted T cells. Gene signatures of relevant immune cell subsets were then validated and employed to define a RT-qPCR based algorithm using plasma samples collected from an independent set of 40 LC patients and 40 matched controls.

At the tumor tissue level, CIBERSORT analysis indicated a significant reduction of cytotoxic T lymphocytes and a concomitant increase of regulatory T cells in MSC high risk patients, characterized by worse prognosis compared to intermediate/low risk patients. A 168 gene signature able to discriminate these two groups was identified. Furthermore, within the LC TCGA datasets the identified signature stratified two groups of patients with different 5-years overall survival (p&lt;0.01). Flow cytometry analysis of PBMC samples confirmed the lower number of lymphocytes at systemic level measured in tumor specimens of MSC high risk patients. This was paralleled by an increase of exhausted T cells as well as classical, inflammatory and monocytic MDSCs. By comparing LC cases and controls an algorithm composed by four immune cell subsets resulted in 0.91 and 0.72 AUC values in the training and validation set, respectively. Based on these results a 14 immune related gene signature was finally developed and tested on samples of the validation set, where an AUC of 0.75 was observed.

Overall, these findings suggest that immunosuppressive features at tumour and systemic discriminate LC patients with worse outcome. Molecular-based tests able to recapitulate these features could be easily moved into the clinical practice.

Citation Format: Mattia Boeri, Veronica Huber, Orazio Fortunato, Ugo Pastorino, Licia Rivoltini, Gabriella Sozzi. Immunosuppressive features characterize tumor tissues and peripheral blood of lung cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3377.