Inactivation of Fbxw7 Impairs dsRNA Sensing and Confers Resistance to PD-1 Blockade

Cancer Discov. 2020 Sep;10(9):1296-1311. doi: 10.1158/2159-8290.CD-19-1416. Epub 2020 May 5.

Abstract

The molecular mechanisms leading to resistance to PD-1 blockade are largely unknown. Here, we characterize tumor biopsies from a patient with melanoma who displayed heterogeneous responses to anti-PD-1 therapy. We observe that a resistant tumor exhibited a loss-of-function mutation in the tumor suppressor gene FBXW7, whereas a sensitive tumor from the same patient did not. Consistent with a functional role in immunotherapy response, inactivation of Fbxw7 in murine tumor cell lines caused resistance to anti-PD-1 in immunocompetent animals. Loss of Fbxw7 was associated with altered immune microenvironment, decreased tumor-intrinsic expression of the double-stranded RNA (dsRNA) sensors MDA5 and RIG1, and diminished induction of type I IFN and MHC-I expression. In contrast, restoration of dsRNA sensing in Fbxw7-deficient cells was sufficient to sensitize them to anti-PD-1. Our results thus establish a new role for the commonly inactivated tumor suppressor FBXW7 in viral sensing and sensitivity to immunotherapy. SIGNIFICANCE: Our findings establish a role of the commonly inactivated tumor suppressor FBXW7 as a genomic driver of response to anti-PD-1 therapy. Fbxw7 loss promotes resistance to anti-PD-1 through the downregulation of viral sensing pathways, suggesting that therapeutic reactivation of these pathways could improve clinical responses to checkpoint inhibitors in genomically defined cancer patient populations.This article is highlighted in the In This Issue feature, p. 1241.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Animals
  • Antibodies, Monoclonal, Humanized / pharmacology
  • Antibodies, Monoclonal, Humanized / therapeutic use
  • Cell Line, Tumor / transplantation
  • DEAD Box Protein 58 / genetics
  • DEAD Box Protein 58 / metabolism
  • Disease Models, Animal
  • Drug Resistance, Neoplasm / genetics*
  • F-Box-WD Repeat-Containing Protein 7 / genetics*
  • F-Box-WD Repeat-Containing Protein 7 / metabolism
  • Gene Expression Regulation, Neoplastic / immunology
  • HeLa Cells
  • Humans
  • Immune Checkpoint Inhibitors / pharmacology*
  • Immune Checkpoint Inhibitors / therapeutic use
  • Interferon-Induced Helicase, IFIH1 / genetics
  • Interferon-Induced Helicase, IFIH1 / metabolism
  • Loss of Function Mutation
  • Male
  • Mice
  • Mutagenesis, Site-Directed
  • Programmed Cell Death 1 Receptor / antagonists & inhibitors
  • RNA, Double-Stranded / immunology
  • RNA, Double-Stranded / metabolism
  • Receptors, Immunologic / genetics
  • Receptors, Immunologic / metabolism
  • Skin Neoplasms / drug therapy*
  • Skin Neoplasms / genetics
  • Skin Neoplasms / immunology
  • Skin Neoplasms / pathology
  • Tumor Microenvironment / genetics
  • Tumor Microenvironment / immunology

Substances

  • Antibodies, Monoclonal, Humanized
  • F-Box-WD Repeat-Containing Protein 7
  • FBXW7 protein, human
  • Fbxw7 protein, mouse
  • Immune Checkpoint Inhibitors
  • PDCD1 protein, human
  • Programmed Cell Death 1 Receptor
  • RNA, Double-Stranded
  • Receptors, Immunologic
  • pembrolizumab
  • DDX58 protein, human
  • IFIH1 protein, human
  • DEAD Box Protein 58
  • Interferon-Induced Helicase, IFIH1