IL-12-secreting CAR-T cells reprogram the tumor microenvironment and improve efficacy against heterogeneous models of glioblastoma.

BACKGROUND: Glioblastoma (GBM) remains uniformly lethal due to pronounced intratumoral heterogeneity and a highly immunosuppressive microenvironment that limits the efficacy of targeted therapies. METHODS: We engineered chimeric antigen receptor (CAR) T cells targeting Epidermal Growth Factor Receptor variant III (EGFRvIII) and armored them with a single-chain interleukin-12 (scIL12) payload. These cells were tested in syngeneic, orthotopic GBM mouse models exhibiting heterogeneous EGFRvIII expression. CAR T cells were delivered intracranially without lymphodepletion. RESULTS: Intracranial administration of scIL12-secreting CAR-T cells eradicated tumors without requiring lymphodepletion, achieving 50% long-term survival. Survival benefits depended entirely on endogenous CD8+ T cells, as efficacy was abolished in CD8-deficient hosts and unaffected by natural killer cell depletion. Notably, therapeutic efficacy was abrogated by lymphodepletion, underscoring the necessity of an intact endogenous immune response. Mechanistically, scIL12 enhanced CAR-T cell persistence and reprogrammed tumor-associated microglia, indicating potential antigen spreading through polyclonal endogenous CD8+T cell responses, which facilitate the elimination of EGFRvIII-negative tumor cells. CONCLUSIONS: This study demonstrates the pleiotropic benefits of IL-12 armored CAR-T cells with improved targeting of antigen-positive tumor cells and simultaneous remodeling of the microenvironment to engage adaptive immunity against antigen-negative clones. This strategy offers a potential clinically actionable approach to improve outcomes in GBM by circumventing the need for toxic lymphodepletion and addressing tumor heterogeneity.

Duke Scholars

Author John Howard Sampson Neurosurgery

Author Anoop Patel Neurosurgery

Author Katayoun Ayasoufi Neurosurgery