IDDF2022-ABS-0247 YTHDF1-EZH2-il-6 axis fuels anti-PD-1 resistance in nash-HCC

Background

Non-alcoholic steatohepatitis (NASH) has become a growing impact as a risk factor for HCC, while it was reported that NASH precluded efficient anti-tumour surveillance in the context of HCC immunotherapy and limited the therapeutic options of NASH-HCC patients. Thus, identifying the potential therapeutic targets that overcome the resistance to anti-PD-1 therapy may provide new potential targets in NASH-HCC.

Methods

The effect of Ythdf1 on the tumorigenesis of NASH-HCC was evaluated using hepatocyte-specific Ythdf1 overexpressed mice in vivo. Immune cell composition was analyzed by single-cell RNA-sequencing, flow cytometry and immunohistochemically staining. The underlying mechanisms of YTHDF1 in NASH-HCC were identified by integrative RNA-sequencing, m⁶A methylated RNA immunoprecipitation sequencing, YTHDF1 RNA immunoprecipitation sequencing and Ribosome-profiling analyses. The therapeutic potential of targeting Ythdf1 was elucidated by systemic administration of siYthdf1 encapsulated in lipid nanoparticles (LNP).

Results

Here we showed that YTHDF1, an m⁶A reader, is upregulated in the tumor area of NASH-HCC patients and mouse models compared with adjacent normal tissue. Liver-specific Ythdf1 overexpression facilitated the tumorigenesis of NASH-HCC. Single-cell RNA-sequencing revealed that Ythdf1 overexpression increased the induction of MDSC and decreased the population of cytotoxic CD8+ T cells, which were further confirmed by flow cytometry and immunostaining. Multi-omics studies and a co-culture system illustrated a hepatoma cell-intrinsic YTHDF1-EZH2-IL-6 pathway that modulates MDSC induction and cytotoxic CD8+ T cell dysfunction. Combination therapy with Ythdf1 depletion and anti-PD-1 antibody treatment resulted in synergistic effects on tumor regression compared with either treatment alone. Furthermore, targeting Ythdf1 using the Food and Drug Administration (FDA) approved LNP encapsulated siRNA system significantly increased the efficacy of the anti-PD-1 blockade in the preclinical NASH-HCC mouse model.

Conclusions

Our study identifies a novel epitranscriptome axis and immune modulation axis of YTHDF1-EZH2-IL6, which renders CD8+ T cell dysfunction via MDSC-mediated immunosuppression. Targeting Ythdf1 using LNP formulation in combination with anti-PD-1 antibody may improve antitumor efficacy in the preclinical NASH-HCC mouse model, suggesting a new therapeutic target to improve NASH-HCC immunotherapy.