Meningioma microenvironment harbors a rich immune landscape that evolves with biological state

Mechanisms driving aggressive meningiomas remain poorly understood. Given the pivotal role of the immune microenvironment in tumor progression, we developed a comprehensive atlas of the meningioma microenvironment, with a view toward identifying modifiable opportunities.

The immune microenvironment of 2,727 meningiomas was profiled using orthogonal methodologies, including 24 with mass cytometry, 24 single-cell RNAseq, 1,437 bulk RNAseq, 1,125 DNA methylation, 117 multiplex immunofluorescence, as well as that of 5 paired peripheral blood samples and 10 human meninges. Patient-derived organotypic tumor spheroids (PDOTS) were established to assess the effect of STING stimulation combined with anti-PD-1 treatment.

We revealed a rich immune infiltration in meningioma, among the highest across 34 human cancer types (n = 12,188). Macrophages predominated in meningioma microenvironment, in contrast to the lymphoid dominance of peripheral blood, with meninges exhibiting an intermediate immune profile between meningiomas and peripheral blood. Cellular states and phenotypes of both immune and tumor cells shifted during tumor progression, with aggressive meningiomas possessing earlier-stage, immunosuppressive immune cells and proliferative tumor cells. Using ex vivo meningioma PDOTS, we demonstrated inducible responses to STING activation, marked by elevated cytokine release, which were synergistic when combined with PD-1 blockade.

These findings offer an extensive resource on the cellular heterogeneity of the meningioma microenvironment and provide a framework for rational therapeutic modeling and strategy development.