Abstract 3497: Glioma Immune Microenvironment Composition Calculator (GIMiCC): A method of estimating the proportions of eighteen key cell types from human brain tissue assayed using Illumina DNA methylation microarray technology

Abstract Precise detection of both tumor subclass and immune composition is critical in the pursuit of personalized immunotherapeutic treatment strategies for glioma. DNA methylation (DNAm) biomarkers are promising on both fronts. DNAm-based biomarkers for molecular classification have been developed and integrated into World Health Organization (WHO) diagnostic criteria. However, prediction of the tumor microenvironment is not as well defined. To fill this gap, we present GIMiCC, an approach for cellular deconvolution of DNAm microarray data for four WHO 2021 tumor subclasses: glioblastoma, oligodendroglioma, grade 2/3 astrocytoma and grade 4 astrocytoma. Using data from 17 isolated cell types, we describe the derivation of the deconvolution libraries and test the method on independent datasets from the Cancer Genome Atlas (TCGA) and the DKFZ molecular neuropathology classifier (PMID: 29539639). We utilize GIMiCC to illustrate that DNAm-based glioma classification is unlikely to be biased by compositional variation. In addition, we utilize GIMiCC to identify composition independent DNAm alterations that are associated with high immune infiltration. Our future work aims to optimize GIMiCC and advance the clinical evaluation of glioma with this new tool. Citation Format: Steven C. Pike, John K. Wiencke, Ze Zhang, Annette M. Molinaro, Devin C. Koestler, Brock C. Christensen, Karl T. Kelsey, Lucas A. Salas. Glioma Immune Microenvironment Composition Calculator (GIMiCC): A method of estimating the proportions of eighteen key cell types from human brain tissue assayed using Illumina DNA methylation microarray technology [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3497.