Observational study identifies four immune subtypes in newly-diagnosed glioma grades 2-4 among 354 patients

Background: Gliomas are heterogeneous tumors with poor outcomes following current therapies, including immunotherapy. The tumor microenvironment (TME) is a critical determinant of therapeutic response in gliomas. We have classified the immune TME of gliomas by multiplex immunofluorescence (mIF). Methods: Tissue taken at initial resection from 354 patients with newly-diagnosed glioma grades 2-4 were analyzed using three mIF panels of markers for T, B, and myeloid cells. Tumor cores were characterized by the relative abundances of: (i) 15 primary immune phenotypes, (ii) 96 secondary immune phenotypes, and, (iii) 29 biologically meaningful multi-marker immune phenotypes. Results: Using unsupervised cluster analysis of WHO grade 4 gliomas we identified four subtypes , {beta}, {gamma}, and {delta} that were internally reproducible. Immune subtype was characterized by high abundance of antigen-presenting cells (APCs) and low levels of MHC II- monocytes. Subtype {beta} was high in regulatory T cells and myeloid cells, but low in lymphocytes with effector functions. Subtype {gamma} displayed high abundance of immune cell phenotypes, particularly lymphocytes with effector or helper functions. Subtype {delta} was low in lymphoid and myeloid immune phenotypes and APCs, with poorer outcomes. Grade 3 tumors could also be classified into , {beta}, {gamma}, and {delta} subtypes, indicating generalizability of these immune TME subtypes across high grade gliomas. Conclusions: We have identified internally reproducible criteria for classifying gliomas according to the immune microenvironment, findings that could aid our understanding of the natural progression of low- and high-grade gliomas and inform the rational application of immune-oncologic therapeutic interventions.