685 Characterization of molecular and spatial diversity of macrophages in hepatocellular carcinoma

Background Hepatocellular carcinoma (HCC) has a dismal prognosis, and though checkpoint blocking antibodies have significantly improved patient outcome, many patients remain left out, highlighting the need to identify additional immune target enhance therapeutic immunity. Macrophages (MF) are an abundant heterogeneous population in tumor microenvironment (TME), associated with poor prognosis multiple types, including HCC, however, their molecular functional diversity is still poorly understood. Methods We analyzed spatial organization patterns of cells within TME adjacent tissue 26 resected HCC lesions using single-cell RNA sequencing multiplex immunohistochemistry (IHC). Results found that Kupffer cells, self-renewing tissue-resident macrophages liver tissue, lacking from TME, which dominated by monocyte-derived macrophages. ScRNAseq followed high-resolution clustering identified distinct MF programs macrophage compartment. One subset expressed shared signature monocytes FCN1, S100A8 T cell activation genes like CXCL9 IL32. Conversely, one FOLR2, SEPP1 complement (C1Qs), program KC include another intratumoral enriched for expression TREM2 GPNMB. Guided these results, we developing IHC antibody panel allows visualize localization TME. Intratumoral interface with, potentially regulate, compartment analyzing our treatment-naïve cohort treated neoadjuvant anti-PD-1 therapy ( NCT03916627 ) study co-localization direct interaction physically-interacting (PICseq). This analysis enables us cell-cell contact preliminary demonstrates enrichment immunosuppressive phenotype. also transcriptomic map will corroborated patients. Conclusions Taken together, data provide new understanding highlight presence specific immunoregulatory unique lesions, subsets be directly interacting modulating anti-tumor responsiveness. Our patients, allow correlate programs, interaction, clinical response, inform trials targeting populations so as improve efficacy cancer immunotherapy. Trial Registration Ethics Approval Samples non-involved were obtained surgical specimens undergoing resection at Mount Sinai Hospital (New York, NY) after obtaining informed consent accordance protocol reviewed approved Institutional Review Board Icahn School Medicine (RUTH Human Subjects Electronic Submission System 18–00407 20–04150) collaboration Biorepository Department Pathology.