Tumor-Infiltrating T Cells in EBV-Associated Gastric Carcinomas Exhibit High Levels of Multiple Markers of Activation, Effector Gene Expression, and Exhaustion

Abstract

Epstein–Barr virus (EBV) is a gamma-herpesvirus associated with 10% of all gastric cancers (GCs) and 1.5% of all human cancers. EBV-associated GCs (EBVaGCs) are pathologically and clinically distinct entities from EBV-negative GCs (EBVnGCs), with EBVaGCs exhibiting differential molecular pathology, treatment response, and patient prognosis. However, the tumor immune landscape of EBVaGC has not been well explored. In this study, a systemic and comprehensive analysis of gene expression and immune landscape features was performed for both EBVaGC and EBVnGC. EBVaGCs exhibited many aspects of a T cell-inflamed phenotype, with greater T and NK cell infiltration, increased expression of immune checkpoint markers (BTLA, CD96, CTLA4, LAG3, PD1, TIGIT, and TIM3), and multiple T cell effector molecules in comparison with EBVnGCs. EBVaGCs also displayed a higher expression of anti-tumor immunity factors (PDL1, CD155, CEACAM1, galectin-9, and IDO1). Six EBV-encoded miRNAs (miR-BARTs 8-3p, 9-5p, 10-3p, 22, 5-5p, and 14-3p) were strongly negatively correlated with the expression of immune checkpoint receptors and multiple markers of anti-tumor immunity. These profound differences in the tumor immune landscape between EBVaGCs and EBVnGCs may help explain some of the observed differences in pathological and clinical outcomes, with an EBV-positive status possibly being a potential biomarker for the application of immunotherapy in GC.

The EBV Gastric Cancer Resource (EBV-GCR): A Suite of Tools for Investigating EBV-Associated Human Gastric Carcinogenesis

“…In particular, EBVaGCs are "immune hot" tumors with higher levels of MHC I and II expression and cytotoxic T cell infiltration and activation when compared to EBVnGCs. [12,13,15,16,47]. Due to their unique immune features, understanding how EBVaGCs differ in relation to EBVnGCs may help elucidate the underlying mechanisms of EBV-mediated changes in the tumor immune landscape and may eventually result in better treatment options for EBVaGC patients.…”

“…It is estimated that EBV is the causative agent of around 10% of all gastric cancer (GC) cases worldwide, though relative proportions differ by region [10,11]. Furthermore, EBVaGCs are molecularly and pathologically distinct entities from EBV-negative GCs (EBVnGCs), with higher survival rates, male-dominant incidence, genome-wide promoter hypermethylation, increased T cell infiltration, as well as higher levels of MHC-I and MHC-II expression [12][13][14][15][16]. Additionally, several EBV-associated proteins and 44 miRNAs originating from the Bam-HI A rightward transcripts (miR-BARTs) are consistently expressed in EBVaGCs, likely contributing to the oncogenesis and progression of EBVaGCs [17,18].…”

The viral etiology of EBV-associated gastric cancers contributes to their unique pathology, clinical outcomes, treatment responses and immune landscape

“…Furthermore, additional sequencing of TCGA GC tissue samples have yielded datasets for expression levels of EBV-encoded mRNAs ( 201 ) and miRNAs ( 87 ), compilation of immune landscape features ( 298 ), and standardized patient outcome data ( 299 ). As one example of the utility of this data, bioinformatic comparisons confirmed that the EBVaGC TME exhibits many aspects of a T cell-inflamed phenotype, with greater T and NK cell infiltration, increased expression of many immune checkpoint markers (BTLA, CD96, CTLA4, LAG3, PD1, TIGIT and TIM3), and multiple T cell effector molecules in comparison with EBVnGCs ( 300 ).…”

Advances and key focus areas in gastric cancer immunotherapy: A comprehensive scientometric and clinical trial review (1999-2023)

“…Post-2020, propelled by technological advancements, breakthroughs such as the use of single-cell RNA sequencing in GC cells and transcriptome analysis of peritoneal cancer samples from patients with GAC have emerged, enriching our understanding of tumor biology and uncovering novel immunotherapy targets[ 111 , 112 ]. Notably, EBV-positive status has been identified as a potential biomarker for EBV-associated GC, paving the way for future studies[ 113 ].…”