Abstract 3664: High frequency of a circulating monocytic subpopulation of myeloid-derived suppressor cells predicts worst clinical outcome in untreated non-small lung cancer patients

Background: The immune system can either prevent and control the tumor growth or promote tumor escape. Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population of immature cells with immune suppressive properties and their overexpression seems to confer a worse prognosis in cancer patients. Objective: The aim of the study was to investigate the presence of new phenotypically immature subpopulations of MDSCs which could be associated with advanced/metastatic NSCLC patients' clinical outcome. Materials & Methods: Circulating subtypes of MDSCs (monocytic and granulocytic), as well as the CD4+ , CD8+ , dendritic (DC), monocytes and B cells were assessed in peripheral blood of of chemotherapy-naive patients with advanced/metastatic NSCLC (n=134) and healthy controls (n=28) were analyzed using flow cytometry. The phenotypic characterization of MDSCs subpopulations was determined in strictly immature myeloid cells. A correlation between the levels of MDSCs and other tested immune cells as well as their association with overall (OS) and progression- free survival (PFS) was evaluated; high expression of MDSCs was defined as the percentage of the cells above the 90% percentile of the controls. Results: Two monocytic [M-MDSC: CD14+CD15-CD11b+CD33+HLA-DR-Lin- and CD14+CD15+CD11b+CD33+HLA-DR-Lin-] and a granulocytic [G-MDSC: CD14-CD15+CD11b+CD33+HLA-DR-Lin-] subpopulation of MDSCs were significantly increased (p Conclusion: The data provide evidence that the increased frequency of two new M-MDSC subpopulations in patients with advanced/metastatic NSCLC is associated with an unfavorable clinical outcome. Citation Format: Eleni Kyriaki Vetsika, Filippos Koinis, Marianthi Gioulmpasani, Despoina Aggouraki, Anna Koutoulaki, Eirini Skalidaki, Dimitris Mavroudis, Vassilis Georgoulias, Athanasios Kotsakis. High frequency of a circulating monocytic subpopulation of myeloid-derived suppressor cells predicts worst clinical outcome in untreated non-small lung cancer patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3664. doi:10.1158/1538-7445.AM2014-3664