10036-IM-3 SPATIAL AND GENOMIC ANALYSES FOR THE CONSTRUCTION OF TERTIARY LYMPHOID STRUCTURE IN GLIOBLASTOMA

Abstract

Abstract BACKGROUND Recently, the presence of tertiary lymphoid structure (TLS), composed mainly of intratumoral B cells, has been reported as a favorable prognostic factor in various types of cancer. However, in glioblastoma, TLS has not been well studied though increased B-cell infiltration was likely to be related to improved prognosis. In this study, we performed spatial and genomic analyses in human glioblastoma, focusing on TLS. METHODS We evaluated lymphocytic infiltration by immunostaining in 54 cases. Flow cytometry was conducted on 12 prospective samples. RNA-sequencing (RNA-seq) was performed in 43 cases to compare those with and without TLS by differential gene expression (DGE) analysis and Gene Set Enrichment Analysis (GSEA). RESULTS TLS was detected in 5 (9.3%) of the 54 cases. Flow cytometry showed that 3 cases with TLS by immunostaining had higher numbers of T and B cells than those without TLS. DGE analysis showed increased gene expression related to the T cell activation marker (TNFRSF9), chemokine (CCL5), etc., in patients with TLS. GSEA also confirmed the activation of immune responses such as adaptive immune response and B cell receptor signaling pathway. We are currently validating these data with spatial transcriptome analysis and investigating the TLS formation in detail. DISCUSSION Although several TLS signatures and TLS components have been reported so far, the formation mechanism of TLS is still unknown. In addition, to our knowledge, there are no reports yet on spatial transcriptome analysis in multiple cases of glioblastoma focusing on the presence of TLS. CONCLUSION We analyzed a total of 54 glioblastoma cases by immunostaining. RNA-seq and spatial transcriptome analysis were performed to assess TLS in glioblastoma comprehensively.