The Ratio between Monocytic Myeloid Derived Suppressor Cells/Monocytes and Dendritic Cells is A Prognostic Intratumoral and Blood Biomarker for Survival of Epithelial Ovarian Cancer Patients

Predictive biomarkers are essential for tailoring therapy of patients with epithelial ovarian cancer (EOC). In this study, various immune populations in both tumor tissue and blood samples from EOC patients were analyzed to identify an easy accessible biomarker. The frequencies of circulating immune cells were determined by flow cytometry and subsequent analysis by opt SNE and FLOWSOM using OMIQ in 36 EOC patients. Primary tumor material (n = 21) was analyzed by multiplex immunofluorescence using Vectra imaging and InForm software. Data were related to overall survival using Kaplan–Meier curves and log-rank testing. A low ratio between mMDSC to DC (p = 0.0004), total monocyte to DC (p = 0.0026), mMDSC to CD19hi B cells (p = 0.0013) and monocyte to CD19hi B cells (p = 0.003) in blood was associated with prolonged survival in EOC patients. Importantly, low mMDSC to DC (p = 0.006) and CD14+HLA-DR+ monocyte to DC ratios (p = 0.006) in tumor tissue were also strongly prognostic for better survival. This is the first study showing that both the intratumoral and systemic balance between two cell types functions as prognostic biomarkers for EOC survival. Validation of their predictive power is ongoing in a prospective study and clinical immunotherapy trial.