Baseline Circulating Myeloid-Derived Suppressor Cells And Response To Pd-1 Inhibitor In Non-Small Cell Lung Cancer Patients.

145Background: Inhibitors of immune checkpoint PD-1/PD-L1 (ICI) have become a care standard in non-small cell lung cancer (NSCLC). Despite promising results, some patients cannot take advantage of immunotherapy effects. Nowadays, neither predictive nor prognostic circulating biomarkers have been found in order to select patients or to predict response to ICI. Myeloid-derived suppressor cells (MDSC) are potent immunity suppressors and may represent both a potential prognostic and a predictive biomarker. Methods: Peripheral blood samples regarding 54NSCLC patients treated with nivolumab and 5 healthy donors were prospectively included. Early-MDSC: e-MDSC (LIN-/CD14-/CD15-/HLA-DR-/CD33+), monocytic-MDSC: M-MDSC (HLA-DR low/-/CD14+/CD15-/CD11b+), polymorphonuclear-MDSC: PMN-MDSC (HLA-DR low/-/CD14-/CD15+/CD11b+) were analyzed through flow cytometry. MDSC percentage was calculated from viable peripheral blood mononuclear cells. We assessed if e-MDSC,M-MDSC and PMN-MDSC levels detected before anti-PD-1 therapy ...