EACR26-1858

Dura-associated immune cell hubs drive effector T-cell responses to glioblastoma

M. Kilian^1,2, M. Schulz³, C. Dierssen⁴, Z. Li⁵, A. Paul⁴, C. Faust Akl¹, M. Prinz^3,6, M. Platten^4,7, F. Quintana^1,2

¹Ann Romney Center for Neurologic Diseases, Brigham and Women’s Hospital, Harvard Medical School, Boston, United States
²Broad Institute of MIT and Harvard, Cambridge, United States
³Institute of Neuropathology, Faculty of Medicine, University of Freiburg, Freiburg, Germany, Freiburg, Germany
⁴Clinical Cooperation Unit (CCU) Neuroimmunology and Brain Tumor Immunology, German Cancer Research Center (DKFZ), Heidelberg, Germany
⁵Ann Romney Center for Neurologic Diseases, Brigham and Women’s Hospital, Harvard Medical, Boston, United States
⁶Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
⁷Department of Neurology, Medical Faculty Mannheim, Mannheim Center for Translation Neuroscience (MCTN), Heidelberg University, Heidelberg, Germany

Introduction:

The meninges play a critical role in the immunosurveillance of the central nervous system that itself is sparsely infiltrated by peripheral immune cells. The meninges and in particular the dura have recently been described as important sites for the control of immune responses in the CNS in the context of autoimmunity and neurodegeneration. The contribution of the dural immune environment to glioblastoma immune responses, however, remains elusive.

Material and method:

Using single-cell RNA sequencing and T-cell receptor tracking to analyze a unique cohort of GBM clinical samples and mouse-preclinical models in combination with genetic perturbations, photoconvertible mice, in vivo mRNA delivery and engineered human CAR T cells, we identified MHC class II-dependent immune cell clusters in the dura that promote T-cell responses to GBM.

Result and discussion:

We found that dura-activated tumor-reactive CD8+ T cells migrate from dura immune cell clusters to the tumor microenvironment and display enhanced and sustained effector functions against GBM. By the means of clonal tracing, we tracked dura-activated T cells in the GBM tumor microenvironment and identified a transcriptional signature of dura-activated T cells. In human GBM and matched dura samples, we detected shared clonotypes between tumor and dura as well as increased immune cell infiltration in GBM-associated dura. In mechanistic studies we identified Stat5-signaling and alarmin expression in dural immune cell clusters as drivers of T cell cytotoxicity. Local lipid nanoparticle-based in vivo delivery of mRNA encoding an engineered alarmin to CNS-border tissues improved CD8+ T-cell effector function and persistence and prolonged survival in glioma-bearing mice.

Conclusion:

In summary, we identified the dura as a site for the induction of GBM-reactive CD8+ T cells with improved effector functions. We show that tumor-derived antigens are presented in the dura and activate tumor-specific T cells. Dura-primed T cells migrate to the tumor microenvironment and are characterized by a defined transcriptional signature and sustained anti-tumor effector functions in mouse and human. These findings define a previously unknown role for the dura in the control of the T-cell response to GBM, and identify novel targets for therapeutic intervention.