Abstract 5296: Hepatocellular carcinoma resistance and recurrence to anti-PD-1 therapy is associated with tumor heterogeneity and plasticity driven by MYC

Abstract Hepatocellular carcinoma (HCC) is the most prevalent type of liver cancer and a major cause of cancer-related deaths worldwide. HCC is characterized by low survival rates and a high incidence of recurrence. Systemic therapy responses are observed in only a small proportion of HCC patients. Our spatial transcriptomics (ST) analysis of HCC tumors from patients treated with anti-PD-1 and cabozantinib (a multi-tyrosine kinase inhibitor) suggested that immunotherapy resistance is driven by cancer cell heterogeneity, tumor microenvironment (TME) dynamics, and cancer cell plasticity. These mechanisms were detected in an HCC sample collected from a responder who later experienced recurrence. To understand the genomic drivers of resistance and recurrence in HCC, we performed new bioinformatic analyses to investigate the molecular mechanisms associated with HCC plasticity that result in anti-PD-1 resistance. Across our ST samples, we observed up-regulation of oncogenic and immune evasion mechanisms following anti-PD-1 treatment. Interestingly, these signaling pathways share a common upstream modulation by MYC. Gene set enrichment analysis identified a significant upregulation of the MYC pathway in immune-poor cancer regions. Spatially weighted correlation analysis revealed that MYC upregulation is colocalized with cancer cell-intrinsic pathways, such as proliferation, metabolism, and cell plasticity, and is spatially exclusive with immune-related pathways, including antigen presentation and interferon-gamma response. Moreover, intercellular interaction analysis showed that MYC-upregulated cancer cells engage in crosstalk with cancer-associated fibroblasts (CAFs) via PDGF-PDGFR signaling, which is associated with the epithelial-mesenchymal transition (EMT) process, a hallmark of cell plasticity. Our findings were validated in additional anti-PD-1-treated HCC single-cell and ST public datasets, confirming that therapy-reinvigorated lymphocytes neutralize only MYC-downregulated HCC cells, leaving MYC-high HCC cells to survive. These residual HCC cells potentially become the source of tumor recurrence. Our findings highlight MYC as a key regulator of therapeutic resistance and immune suppression in HCC, potentially serving as a target for future interventions to delay anti-PD-1 treatment relapse and improve patient outcomes. Citation Format: Shuming Zhang, Ludmila Danilova, Jacob T. Mitchell, Iris Kwon, Aleksander S. Popel, Mark Yarchoan, Elizabeth M. Jaffee, Elana J. Fertig, Luciane T. Kagohara. Hepatocellular carcinoma resistance and recurrence to anti-PD-1 therapy is associated with tumor heterogeneity and plasticity driven by MYC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5296.