Mismatch repair deficiency drives malignant progression and alters the tumor immune microenvironment in glioblastoma models
Montserrat Puigdelloses Vallcorba, Nishant Soni, Seung-Won Choi, Kavita Rawat, Tanvi Joshi, Sam Friedman, Alice Buonfiglioli, Angelo Angione, Zhihong Chen, Gonzalo Piñero, Gabrielle Price, Mehek Dedhia, Raina Roche, Emir Radkevich, Anne M. Bowcock, Deepti Bhatt, Winfried Edelmann, Robert M. Samstein, Timothy E. Richardson, Nadejda M. Tsankova, Alexander M. Tsankov, Ranjit S. Bindra, Raul Rabadan, Juan C. Vasquez, Dolores Hambardzumyan
Montserrat Puigdelloses Vallcorba, Nishant Soni, Seung-Won Choi, Kavita Rawat, Tanvi Joshi, Sam Friedman, Alice Buonfiglioli, Angelo Angione, Zhihong Chen, Gonzalo Piñero, Gabrielle Price, Mehek Dedhia, Raina Roche, Emir Radkevich, Anne M. Bowcock, Deepti Bhatt, Winfried Edelmann, Robert M. Samstein, Timothy E. Richardson, Nadejda M. Tsankova, Alexander M. Tsankov, Ranjit S. Bindra, Raul Rabadan, Juan C. Vasquez, Dolores Hambardzumyan
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Research Article Cell biology Immunology Neuroscience Oncology

Mismatch repair deficiency drives malignant progression and alters the tumor immune microenvironment in glioblastoma models

Abstract

Mutations in DNA mismatch repair (MMR) pathway genes (MSH2, MSH6, MLH1, and PMS2) are linked to acquired resistance to temozolomide (TMZ) and high tumor mutation burden (TMB) in high-grade gliomas (HGGs), including glioblastomas (GBMs). However, the specific roles of individual MMR genes in the initiation, progression, TMB, microsatellite instability (MSI), and resistance to TMZ in gliomas remain unclear. Here, we developed de novo mouse models of germline and somatic MMR-deficient (MMRd) HGGs. Surprisingly, loss of Msh2 or Msh6 did not lead to high TMB, MSI, nor did it confer a response to anti–programmed cell death 1 (anti–PD-1) in GBM. Similarly, human GBM showed discordance between MMR gene mutations and the TMB and MSI. Germline MMRd promoted the progression from low-grade to HGG and reduced survival compared with MMR-proficient (MMRp) tumor–bearing mice. This effect was not tumor cell intrinsic but was associated with MMRd in the tumor immune microenvironment, driving immunosuppressive myeloid programs, reduced lymphoid infiltration, and CD8+ T cell exhaustion. Both MMR-reduced (MMRr) and MMRd GBM were resistant to TMZ, unlike MMRp tumors. Our study shows that N3-(2-fluoroethyl) imidazotetrazine (KL-50), an imidazotetrazine-based DNA targeting agent that induces MMR-independent cross-link–mediated cytotoxicity, was effective against germline and somatic MMRr and MMRd GBMs, offering a potential therapy for TMZ-resistant HGG with MMR alterations.

Authors

Montserrat Puigdelloses Vallcorba, Nishant Soni, Seung-Won Choi, Kavita Rawat, Tanvi Joshi, Sam Friedman, Alice Buonfiglioli, Angelo Angione, Zhihong Chen, Gonzalo Piñero, Gabrielle Price, Mehek Dedhia, Raina Roche, Emir Radkevich, Anne M. Bowcock, Deepti Bhatt, Winfried Edelmann, Robert M. Samstein, Timothy E. Richardson, Nadejda M. Tsankova, Alexander M. Tsankov, Ranjit S. Bindra, Raul Rabadan, Juan C. Vasquez, Dolores Hambardzumyan

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Figure 1

Distinct distributions of mutation types and correlations with TMB highlight the functional divergence of MMR genes in GBM.

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Distinct distributions of mutation types and correlations with TMB highl...
(A) Positive selection of frequently altered genes in GBM tumors. (B) Principal component (PC) analysis of frequently altered genes in the GBM cohort based on mutation type representation. (C) Proportions of mutation types for each gene. (D) Comparison of TMBs according to mutation type for each MMR gene. (E) Proportion of the HM phenotype in GBMs with MMR gene mutations. The Kruskal-Wallis test was used, followed by pairwise Wilcoxon rank-sum tests for post hoc analysis. P values were adjusted for multiple comparisons using the Bonferroni method (D). Data are presented as the mean ± SD. *P < 0.05, **P < 0.01, and ***P < 0.001. Mis, missense; Trunc, truncation.