BIOM-20. NEAT1 EXPRESSION IS ASSOCIATED WITH GLIOBLASTOMA PATIENT RESPONSE TO IMMUNE CHECKPOINT INHIBITORS

Abstract

Abstract Glioblastoma (GBM) is the most common and aggressive primary brain cancer. Despite advances in therapeutic intervention, including maximal tumor resection, chemotherapy, and radiotherapy, GBM patient median survival remains approximately 20.9 months. A promising approach to overcome current therapeutic challenges is the use of inhibitors of immune checkpoints, such as PD-1/PD-L1, which have been demonstrated to be effective against many different solid cancers. Despite the strong interest in applying these strategies to GBM, clinical studies evaluating the efficacy of monoclonal antibodies against PD-1/PD-L1 have yielded disappointing results. However, an analysis of the data from these studies, considering clinical factors such as MGMT promoter methylation and the use of steroids, indicated that immune checkpoint inhibitor (ICI) therapy may benefit a subset of GBM patients. Moreover, additional clinical studies in GBM have demonstrated the importance of the timing of ICI treatment, although the markers associated with response remain unclear. Therefore, understanding the molecular basis of clinical response to PD-1/PD-L1 inhibitors is critical to identify GBM patients who can benefit from this type of therapy. By analyzing the transcriptomic profile of two different cohorts of GBM patients, we identify NEAT1 as a long noncoding RNA upregulated in GBM patients with longer survival upon anti-PD-1/PD-L1 treatment. Higher expression of NEAT1 was associated with upregulation of the interferon-gamma pathway and downregulation of cell-cycle-related genes. Single-cell RNA-sequencing analysis showed that higher NEAT1 expression in tumor cells correlated with the number of infiltrating macrophages and microglia. Among the GBM immune infiltrates, we found that macrophages and microglia had the highest NEAT1 median expression. Macrophage expression of NEAT1 was associated with enrichment in the TNF-alpha signaling pathway and the regulation of different inflammatory cytokines. Our findings suggest that NEAT1 is an important factor in shaping the tumor-immune microenvironment and a potential marker to predict GBM patient response to ICI.