Single-cell profiling of peripheral and local immune compartments reveal unique genotype-independent prognostic immune signatures across isocitrate dehydrogenase-stratified glioma.

BACKGROUNDSolid tumor immune suppression requires cooperation of tumor cells, local immune cells, peripheral circulating immune cells, and evolution of immune cell trajectories between peripheral and local environments. This study addresses a significant knowledge gap by characterizing peripheral and local immune environments in isocitrate dehydrogenase (IDH) Mutant (IDH-Mut) and IDH wildtype (IDH-WT) gliomas and defines novel immunological states with prognostic relevance across the glioma landscape.

METHODSWe analyzed local and peripheral immune phenotypes in a cohort of 18 (6 IDH-Mut and 12 IDH-WT) gliomas with distinct genetic characteristics using paired human tumor and peripheral blood mononuclear cells (PBMCs) with single-cell RNA-sequencing (scRNA-seq).

RESULTSOur analyses revealed unique intratumoral and peripheral immune cellular ontogenies, including naïve CD4+ T cell enrichment in the IDH-Mut peripheral immune compartment, monocyte enrichment in IDH-WT glioma PBMCs, and emergence of a unique population of GZMH+ CD8+ T cells preferentially in the IDH-Mut microenvironment. Additionally, we found upregulation of TNF-α signaling and inflammatory response pathways in IDH-Mut--glioma-associated peripheral lymphoid cells versus IDH-WT tumors and identified a novel population of microglia-like cells in the peripheral blood of glioma patients with complement-interfacing characteristics. Applying intratumoral transcriptomic deconvolution via The Cancer Genome Atlas revealed genotype-independent, prognostic immune signatures across the malignant glioma landscape.

CONCLUSIONSThis study reveals variable expression of immune phenotypes in adult gliomas stratified by IDH status and characterizes immune compartment and genotype-dependent differences in the immunologic glioma landscape. These genotype-dependent, tumor and circulating immune ontogenies should guide future diagnostic and immunotherapeutic considerations in malignant glioma.