Reversing Epigenetic Gene Silencing to Overcome Immune Evasion in CNS Malignancies

ABSTRACT: Glioblastoma is an aggressive brain malignancy with a dismal prognosis. With emerging evidence that disproves the immune privileged environment in the brain, there is much interest in examining various immunotherapy strategies to treat these incurable cancers. Unfortunately, to date, clinical studies investigating immunotherapy regimens have not provided much evidence of efficacy, leading to questions about the suitability of immunotherapy strategies for these tumors. Inadequate inherent populations of lymphocytes in tumor (TILs) and limited trafficking of systemic circulating T cells into the central nervous system (CNS) likely contribute to the poor response to immunotherapy treatment for primary CNS cancers. This paucity of TILs is in concert with the finding of epigenetic silencing of genes that promote immune cell movement (chemotaxis) to the tumor. In this study we evaluated the ability of GSK126, a blood-brain barrier permeable small molecule inhibitor of EZH2, to reverse the epigenetic silencing of chemokines like CXCL9 and CXCL10. When combined with anti-PD-1 treatment, these IFN driven chemokines promote T cell infiltration, resulting in decreased tumor growth and enhanced survival in immunocompetent murine sub-cutaneous and intracranial tumor syngeneic models of GBM. Examination of the tumor micro-environment revealed that the decrease in tumor growth in the mice treated with the drug combination was accompanied by increased tumor CD8 T cell infiltration along with higher IFN expression. Additionally, a significant increase in CXCR3+ T cells in the draining lymph nodes was also found. Taken together, our data suggests that in glioblastoma, epigenetic modulation using GSK126 could improve current immunotherapy strategies by reversing the epigenetic changes that enable immune cell evasion leading to enhanced immune cell trafficking to the tumor.

ORGANISM(S): Mouse Mus Musculus

TISSUE(S): Tumor Cells

DISEASE(S): Cancer

SUBMITTER: Tyrone Dowdy  

PROVIDER: ST001838 | MetabolomicsWorkbench | Fri Jun 11 00:00:00 BST 2021

REPOSITORIES: MetabolomicsWorkbench