Abstract 2902: Deciphering the function of lipid-associated macrophages in immunotherapy resistance of hepatocellular carcinoma

Abstract Background: Hepatocellular carcinoma (HCC) is a leading cause of cancer-related mortality globally. While immune-checkpoint blockade (ICB) has transformed oncology, its efficacy in HCC is limited by an immunosuppressive tumor microenvironment (TME) and diverse disease etiologies, yielding response rates below 30%. Our prior work identified several key transcriptional and epigenetic drivers of immune exclusion and myeloid-mediated immunosuppression underlying ICB resistance in preclinical models (Gut 2018, 2020, 2023, Sci Transl Med 2021). To develop precise immunotherapies, it is critical to identify the central regulatory nodes within the TME of ICB-resistant patients. Methods: We applied single-cell RNA sequencing (scRNA-seq), single-cell Assay for Transposase-Accessible Chromatin using sequencing (scATAC-seq), and spatial transcriptomics to investigate the TME of HCC patients resistant to ICBs (from trial NCT05873244), with treatment-naïve patients serving as controls. Results: Multi-omics analysis uncovered a subcluster of tumor-associated macrophages (TAMs) characterized by high levels of lipid-associated genes. Bioinformatics analysis of open chromatin regions identified a transcription factor (MTF) that was significantly up-regulated in TAMs from ICB-resistant HCCs but not in treatment-naïve tumors. Spatial transcriptomic profiling and multiplex immunohistochemistry confirmed the co-localization of MTF with the lipid-associated macrophages (LAMs) in patient tumors. Chromatin immunoprecipitation-sequencing in THP-1 cells revealed that MTF binding was enriched in phagocytosis-related genes. Functional studies in macrophage cell lines demonstrated that knockdown or overexpression of MTF modulated phagocytic capacity. Integrated RNA sequencing and Cut Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2902.