Glioblastoma immune landscape remodeling following treatment with CD70-targeted CAR-T cells.

Chimeric antigen receptor (CAR)-T cell therapy has shown limited efficacy in glioblastoma (GB), largely because of the immunosuppressive tumor microenvironment (TME). We have previously demonstrated that the ligand-based mCD70-directed construct mCAR27 specifically eliminates CD70⁺ GB cells in vitro, and induces durable tumor remission with prolonged survival in a syngeneic model of orthotopic GB. Despite the therapeutic promise of CD70 as a GB CAR-T cell target, the impact of CD70-directed CAR-T cells on the brain tumor immune landscape after target interception remains unexplored. Here, we independently confirmed a tumorigenic role for CD70 in murine GB by performing bulk RNA sequencing and in vivo experiments. Next, we applied single-cell RNA sequencing (scRNAseq) to decipher the transcriptome of GB-infiltrating immune cells in immunocompetent mice bearing CD70+ GB after intratumoral mCAR27 therapy. CAR-T cell treatment expanded adoptively transferred cells and was associated with increased endogenous Cd8⁺ T-cell infiltration, alongside a reduction in immunosuppressive populations, including Tregs and anti-inflammatory M2-like macrophages, but also subsets of dendritic and natural-killer cells. CD70 expression was detected on multiple GB-infiltrating immune subsets, notably Tregs and M2-like macrophages. Transcriptionally, mCAR27-mediated GB remission led to a coordinated downregulation of type-I interferon-stimulated genes and immunosuppressive mediators such as Arg1, Tgfbi, Cd274, Pdcd1lg2 and Lag3, coupled with upregulation of genes involved in inflammatory resolution, findings consistent with attenuation of GB-derived inflammatory stress and immunosuppression. Collectively, we showcase that CD70-directed CAR-T cell therapy remodels the post-treatment immune landscape towards resolution of inflammation and reduced immunosuppression, supporting sustained immune surveillance.