Increased immunogenicity of hypermutated SB28 syngeneic glioblastoma is partially mediated by alterations in tumor chemokine expression.
[BACKGROUND] Glioblastoma (GBM) prognosis remains poor, and although immune checkpoint inhibitors (ICI) have transformed the treatment of many tumors, they are ineffective in GBM.
APA
Breen KT, Haynes T, et al. (2025). Increased immunogenicity of hypermutated SB28 syngeneic glioblastoma is partially mediated by alterations in tumor chemokine expression.. Neuro-oncology advances, 7(1), vdaf249. https://doi.org/10.1093/noajnl/vdaf249
MLA
Breen KT, et al.. "Increased immunogenicity of hypermutated SB28 syngeneic glioblastoma is partially mediated by alterations in tumor chemokine expression.." Neuro-oncology advances, vol. 7, no. 1, 2025, pp. vdaf249.
PMID
41624425
Abstract
[BACKGROUND] Glioblastoma (GBM) prognosis remains poor, and although immune checkpoint inhibitors (ICI) have transformed the treatment of many tumors, they are ineffective in GBM. However, response to ICIs occurs in high-tumor-mutational-burden (TMB) GBMs. To address the immunological impact of high TMB in GBM, we created a high TMB syngeneic mouse model from the low TMB SB28 GBM cell line.
[METHODS] We used CRISPR-Cas9 to target murine , , and . Single-cell-sorted clones were characterized by whole exome, bulk RNA-sequencing, and neoantigen prediction. Clones were injected subcutaneously or intracranially with or without anti-PD-1/anti-CTLA4 and dexamethasone.
[RESULTS] Loss of mismatch repair (MMR) proteins Msh2 or Mlh1 increased nonsynonymous mutations. A fraction of mice with intracranial KO but not KO SB28 showed long-term survival with anti-PD-1/anti-CTLA4 treatment plus dexamethasone. Long-term surviving mice from KO SB28 rejected rechallenged subcutaneous tumors. Subcutaneous tumors from clones with increased TMB grew more slowly. This was fully abrogated in null mice for KO but only partially for KO SB28. Hypermutant KO clones spontaneously secreted CXCL10, CCL5, and increased pro-inflammatory chemokines after IFN-γ stimulation. Knockout of or in the highest TMB KO clone restored flank tumor growth, indicating loss of immune response despite elevated TMB.
[CONCLUSION] Mismatch repair-deficient SB28 tumors were more immunogenic, but this was not completely correlated with TMB. Rather, rejection depended on increased secretion of pro-inflammatory chemokines. and loss was not equivalent, suggesting that additional studies are needed to elucidate germline and somatic mismatch repair gene-specific immune alterations.
[METHODS] We used CRISPR-Cas9 to target murine , , and . Single-cell-sorted clones were characterized by whole exome, bulk RNA-sequencing, and neoantigen prediction. Clones were injected subcutaneously or intracranially with or without anti-PD-1/anti-CTLA4 and dexamethasone.
[RESULTS] Loss of mismatch repair (MMR) proteins Msh2 or Mlh1 increased nonsynonymous mutations. A fraction of mice with intracranial KO but not KO SB28 showed long-term survival with anti-PD-1/anti-CTLA4 treatment plus dexamethasone. Long-term surviving mice from KO SB28 rejected rechallenged subcutaneous tumors. Subcutaneous tumors from clones with increased TMB grew more slowly. This was fully abrogated in null mice for KO but only partially for KO SB28. Hypermutant KO clones spontaneously secreted CXCL10, CCL5, and increased pro-inflammatory chemokines after IFN-γ stimulation. Knockout of or in the highest TMB KO clone restored flank tumor growth, indicating loss of immune response despite elevated TMB.
[CONCLUSION] Mismatch repair-deficient SB28 tumors were more immunogenic, but this was not completely correlated with TMB. Rather, rejection depended on increased secretion of pro-inflammatory chemokines. and loss was not equivalent, suggesting that additional studies are needed to elucidate germline and somatic mismatch repair gene-specific immune alterations.