Suppression of antitumor immune signatures and upregulation of VEGFA as IDH-mutant gliomas progress to higher grade

Abstract

OBJECTIVE Several studies have compared the immune microenvironment of isocitrate dehydrogenase (IDH)-wildtype glioma versus IDH-mutant glioma. The authors sought to determine whether histological tumor progression in a subset of IDH-mutant glioma was associated with concomitant alterations in the intratumoral immune microenvironment. METHODS The authors performed bulk RNA sequencing on paired and unpaired samples from patients with IDHmutant glioma who underwent surgery for tumor progression across multiple timepoints. They compared patterns of differential gene expression, overall inflammatory signatures, and transcriptomic measures of relative immune cell proportions. RESULTS A total of 55 unique IDH-mutant glioma samples were included in the analysis. The authors identified multiple genes associated with progression and higher grade across IDH-mutant oligodendrogliomas and astrocytomas. Compared with lower-grade paired samples, grade 4 IDH-mutant astrocytomas uniquely demonstrated upregulation of VEGFA in addition to counterproductive alterations in inflammatory score reflective of a more hostile immune microenvironment. CONCLUSIONS Here, the authors have provided a transcriptomic analysis of a progression cohort for IDH-mutant glioma. Compared with lower-grade tumors, grade 4 astrocytomas displayed alterations that may inform the timing of antiangiogenic and immune-based therapy as these tumors progress.