Abstract 6517: ALDOC as an indicator of HMGB1 blockade combined with checkpoint inhibitor based immunotherapy in GBM patients

Abstract

Abstract Aldolase is an enzyme that takes part in glycolysis by catalyzing a six-carbon intermediate to yield two three-carbon products, requiring ATP. The aldolase family comprises three members, namely ALDOA, ALDOB, and brain-specific ALDOC. Low-grade gliomas and glioblastoma (GBM) are characterized by shared genetic events, including chromosome 1p/19q codeletion, EGFR amplification, and ATRX loss of function, in which ALDOC plays a role. Additionally, ALDOC is responsive to IDH1 mutations. If patients display IDH1 mutations, it is expected that ALDOC performance will be relatively higher. This finding suggests a more favorable prognosis. The ALDOC promoter region's function is impeded by hypermethylation, which declines as glioma progresses. The regulatory mechanisms and implications remain unclear. We established a multi-omics profile and identified several crucial mechanisms activated upon the loss of ALDOC expression. Among these mechanisms, we found HMGB1 to have a key role in linking the immune response, tumor microenvironment, and epigenetic modifications. We compared the proteomic and secretomic platforms in an ALDOC overexpression/knockdown model, which showed abundant HMGB1 expression following ALDOC inhibition. Importantly, there is an inverse correlation between ALDOC expression and HMGB1 protein levels. Additionally, our findings reveal that upregulation of ALDOC promotes its translocation to the nucleus, thereby enhancing its binding affinity with HMGB1. This, in turn, enables extracellular release of HMGB1 in GBM, which triggers signaling via receptors for advanced glycation end-products (RAGE) and several cytokines. Moreover, HMGB1 remodels the immune microenvironment and upregulates multiple immune checkpoint molecules, including PD-L1, PD-L2, B7-H3, and MHCs. Not all GBM models exhibited significant effects when combined with immune checkpoint blockade using HMGB1 blockade. However, ALDOC knockout mice demonstrated poorer survival and treatment efficacy, suggesting that ALDOC may be crucial for a personalized immunotherapy strategy. Citation Format: Yi-Fang Yang, Ming-Hsien Chan, Chi-Long Chen, Michael Hsiao, Yu-Chan Chang. ALDOC as an indicator of HMGB1 blockade combined with checkpoint inhibitor based immunotherapy in GBM patients [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 6517.