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

Abstract

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. To identify the key regulatory nodes connecting KRAS^G12D-driven metabolic adaptations to tumour microenvironment and develop a mechanistic-based combinatorial strategy. 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. 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. 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.