Epigenetic priming induces cancer testis antigens and human endogenous retroviruses in glioma for enhanced T cell responses at single cell resolution (methylation)

Glioblastoma (GBM) is the most common malignant primary brain tumor and remains incurable. Previous work has shown that systemic administration of Decitabine (DAC) induces sufficient expression of NY-ESO-1 in GBM for targeting by adoptive T-cell therapy in vivo. However, the mechanisms by which DAC enhances immunogenicity in GBM remain to be elucidated. Using patient tissue, immortalized glioma cells, and primary patient-derived gliomaspheres, we demonstrate in vitro that basal NY-ESO-1 expression is restricted by promoter hypermethylation in gliomas. DAC treatment of glioma cells specifically inhibits DNA methylation silencing and renders NY-ESO-1 an inducible tumor antigen. Targeting of DAC-induced NY-ESO-1 in primary GBM cells promotes specific and polyfunctional NY-ESO-1 TCR-T cell responses. DAC further upregulates other tumor-associated cancer testis antigens concomitantly with tumor-intrinsic reactivation of human endogenous retroviruses (hERV) and type I interferon. Overall, we demonstrate that DAC promotes an inducible tumor antigen and enhances T cell functionality against GBM. To characterize the effects of Decitabine on primary and immortalized glioma cell lines.