Ovarian Cancer Ascites Enriched for CCL23 Reduces Macrophage-Derived CXCL10 Secretion and Is Associated with Poor Patient Outcomes

<b>Background</b>: Ovarian cancer ascites contributes to the immunosuppressive tumor microenvironment (TME) via macrophage-derived chemokine ligand 23 (CCL23) signaling, T-cell exhaustion, and upregulating pro-inflammatory cytokines. However, the extent to which ascites-derived CCL23 concentrations associate with changes in pro- and anti-inflammatory cytokines and overall patient survival in ovarian cancer patients remains unknown. <b>Methods</b>: CCL23 concentrations and pro-inflammatory cytokines were measured from ascites of stage III and IV epithelial ovarian cancer patients by ELISA and Luminex assays, respectively. Kaplan-Meier survival analysis was performed using patient outcome data from Stanford University Hospital and the Cancer Genome Atlas. The impact of CCL23 peptides on pro-inflammatory cytokine secretion was evaluated in vitro using differentiated THP-1 monocytes. <b>Results</b>: A total of 40 patients were enrolled and CCL23 concentrations were detected in all ascites samples (median = 2.42 ng/mL; range [0.06-6.45]). Reduced survival time corresponded with high CCL23 containing samples (mOS: 3.2 years, [3.9 ng/mL]) versus intermediate (mOS: 6.0 years, [2.5 ng/mL]) or low (mOS: 5.9 years; [1.4 ng/mL]) groups. TGCA analysis of patient outcomes was confirmatory. A significant negative correlation was observed between high CCL23 ascites concentrations versus CXCL10 and soluble PD-1 cytokine levels. High tumor expression of CXCL10 was associated with improved survival (mOS; 5.9 years) versus low CXCL10 expression (mOS; 3.2 years). In vitro, CCL23-stimulated THP-1 macrophages exhibited reduced CXCL10 secretion via STAT-3 activation. <b>Conclusions</b>: High CCL23 concentrations in ovarian cancer ascites reduces CXCL10 secretion from myeloid cells and associates with reduced patient survival.