IDDF2023-ABS-0256 Single-cell landscape of cancer-associated fibroblasts in immunotherapy resistance of hepatocellular carcinoma

BackgroundImmune checkpoint blockade (ICB) therapy has changed the paradigm of hepatocellular carcinoma (HCC) treatment. However, the response rate of ICB therapy remains low (below 20%), which is possibly due to heterogeneity of HCC cells and the tumor microenvironment (TME). Studies have shown that cancer-associated fibroblasts (CAFs) play a crucial role in regulating different TME components in HCC. Although lipid metabolism-associated CAFs have been associated with ICB efficacy in HCC murine model, the roles of other CAF subtypes are not known. Therefore, identifying CAF heterogeneity could increase our understanding of HCC TME and potentially enhance ICB efficacy.MethodsWe conducted single-cell RNA sequencing on tumor biopsy samples from advanced HBV-related HCC patients undergoing a pembrolizumab (anti-PD1) phase II clinical trial (NCT03419481). We analyzed the dynamic changes of the HCC TME before and during anti-PD1 treatment (upon 2-cycle). We used the Seurat and Cellchat package for bioinformatics analysis to investigate the correlations between the proportion change of CAF subtypes and patients’ clinical response and the potential cell-cell interactions between CAF and other TME components.ResultsWe identified four CAF subtypes within the TME: cycling, inflammatory, matrix, and vascular CAFs in our anti-PD1 HCC patient cohort. In the non-responders, the subcluster proportions in cycling CAF (cCAF-MKI67) and matrix CAF-fibroblast activation protein-α (matCAF-FAP) were significantly increased when compared to the responders. Notably, an increase in the proportion of matCAF-FAP upon anti-PD1 treatment was associated with larger tumor size. The matCAF-FAP proportion was positively correlated with two types of immunosuppressive cells, namely regulatory T cells and M2 macrophages. Moreover, a strong chemokine (C-X-C motif) ligand (CXCL) pathway signal was found between matCAF-FAP and regulatory T cells/M2 macrophages in the anti-PD1-non-responders.ConclusionsThe prevalence of matCAF-FAP in HCC tumor may contribute to the establishment of immunosuppressive TME and poor prognosis of patients. Targeting this CAF subtype may overcome the resistance of ICB therapy. Acknowledgments: the CUHK Strategic Seed Funding for Collaborative Research Scheme and the Li Ka Shing Foundation.