USP20 promotes CD8 ⁺ T cell exhaustion and impairs KRAS ^G12D inhibitor efficacy by orchestrating cholesterol metabolism and autophagy in pancreatic cancer

Background The application of the novel KRAS G12D inhibitor in pancreatic ductal adenocarcinoma (PDAC) is currently hindered by adaptive resistance. Metabolic reprogramming is a hallmark of KRAS G12D signalling, yet the mechanisms linking these alterations to immunosuppression and low therapeutic response are poorly defined. Objective To identify the key regulatory nodes connecting KRAS G12D -driven metabolic adaptations to tumour microenvironment and develop a mechanistic-based combinatorial strategy. Design We integrated whole-exome sequencing, untargeted metabolomics and single-cell RNA sequencing of human PDAC specimens to analyse the metabolic-immune landscape. We evaluated therapeutic efficacy using the autochthonous mouse and patient-derived xenograft models. Results We found that KRAS G12D enhanced cholesterol metabolism and promoted CD8 + T cell exhaustion, whereas KRAS G12D inhibition or cholesterol synthesis blockade induced compensatory ULK1-associated autophagy. Cotargeting cholesterol metabolism and autophagy potentiated the antitumour efficacy of the KRAS G12D inhibitor MRTX1133 and alleviated CD8 + T cell exhaustion. Mechanistically, KRAS G12D transcriptionally upregulated USP20 via EGR1, which simultaneously deubiquitinated and stabilised 3-hydroxy-3-methylglutaryl-CoA reductase and ULK1, thereby orchestrating cholesterol metabolism and autophagy-associated survival. Genetic depletion or pharmacological inhibition of USP20 with GSK2643943A suppressed these pathways and restored CD8 + T cell function, improving responses to MRTX1133 and anti-programmed cell death protein-1 (anti-PD-1). In preclinical PDAC models, triple therapy with GSK2643943A, MRTX1133 and anti-PD-1 elicited a robust therapeutic response and induced significant tumour regression. Conclusion USP20 acts as a critical metabolic checkpoint that orchestrates CD8 + T cell exhaustion and therapeutic response. Targeting the USP20–cholesterol–autophagy axis represents a promising strategy to reverse immune suppression and unlock the full potential of KRAS G12D inhibitors in PDAC.