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Published on: January 14, 2014
Isocitrate dehydrogenase mutations suppress STAT1 and CD8+ T cell accumulation in gliomas
Abstract:
Mutations in the isocitrate dehydrogenase genes IDH1 and IDH2 are among the first genetic alterations observed during the development of lower-grade glioma (LGG). LGG-associated IDH mutations confer gain-of-function activity by converting α-ketoglutarate to the oncometabolite R-2-hydroxyglutarate (2HG). Clinical samples and gene expression data from The Cancer Genome Atlas (TCGA) demonstrate reduced expression of cytotoxic T lymphocyte-associated genes and IFN-γ-inducible chemokines, including CXCL10, in IDH-mutated (IDH-MUT) tumors compared with IDH-WT tumors. Given these findings, we have investigated the impact of IDH mutations on the immunological milieu in LGG. In immortalized normal human astrocytes (NHAs) and syngeneic mouse glioma models, the introduction of mutant IDH1 or treatment with 2HG reduced levels of CXCL10, which was associated with decreased production of STAT1, a regulator of CXCL10. Expression of mutant IDH1 also suppressed the accumulation of T cells in tumor sites. Reductions in CXCL10 and T cell accumulation were reversed by IDH-C35, a specific inhibitor of mutant IDH1. Furthermore, IDH-C35 enhanced the efficacy of vaccine immunotherapy in mice bearing IDH-MUT gliomas. Our findings demonstrate a mechanism of immune evasion in IDH-MUT gliomas and suggest that specific inhibitors of mutant IDH may improve the efficacy of immunotherapy in patients with IDH-MUT gliomas.
Insights
Mutations in isocitrate dehydrogenase (IDH) genes in lower-grade gliomas (LGG) reduce CXCL10, hindering T cell response. Inhibiting mutant IDH with IDH-C35 restores CXCL10 and T cell infiltration, improving immunotherapy efficacy in IDH-mutant gliomas.
Area of Science:
- Neuro-oncology
- Cancer Immunology
- Molecular Biology
Background:
- Mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2) are early events in lower-grade glioma (LGG) development.
- IDH mutations lead to the production of the oncometabolite 2-hydroxyglutarate (2HG).
- IDH-mutated (IDH-MUT) tumors show reduced expression of immune-related genes, including CXCL10, compared to IDH-wildtype (IDH-WT) tumors.
Purpose of the Study:
- To investigate the impact of IDH mutations on the tumor immunological microenvironment in LGG.
- To explore the potential of targeting mutant IDH to overcome immune evasion in LGG.
Main Methods:
- Utilized immortalized normal human astrocytes (NHAs) and syngeneic mouse glioma models.
- Introduced mutant IDH1 or treated with 2HG to assess CXCL10 and STAT1 levels.
- Administered IDH-C35, a specific inhibitor of mutant IDH1, to evaluate its effects on immune cell infiltration and immunotherapy efficacy.
- Analyzed gene expression data from The Cancer Genome Atlas (TCGA).
Main Results:
- Mutant IDH1 expression or 2HG treatment reduced CXCL10 levels, correlating with decreased STAT1 production.
- Mutant IDH1 expression suppressed T cell accumulation at tumor sites.
- IDH-C35 treatment reversed CXCL10 reduction and increased T cell infiltration.
- IDH-C35 enhanced the efficacy of vaccine immunotherapy in mice with IDH-MUT gliomas.
Conclusions:
- IDH mutations promote immune evasion in LGG by reducing CXCL10 and T cell infiltration.
- Specific inhibitors of mutant IDH, such as IDH-C35, can reverse this immune suppression.
- Targeting mutant IDH represents a promising strategy to improve immunotherapy outcomes for patients with IDH-MUT gliomas.
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