Epstein-Barr virus (EBV)-associated gastric cancer (EBVaGC) is mediated by EBV-infected malignant cells in gastric intestinal tract. About 10% of gastric carcinoma are EBVaGC worldwide, and over 85,000 patients are developed EBVaGC annually. EBVaGC shows several different aspects with EBV-negative gastric cancer such as clinicopathology, CpG island methylation status and expression of EBV-related genes. Therefore, immunotherapy to treat EBVaGC would be a good approach because expression pattern of EBVaGC is evidently different with that of EBV-negative cells in stomach. Adoptive T cell transfer has been effective for treatment of EBV-positive nasopharyngeal carcinoma (NPC) and lymphomas, which express similar EBV antigens to those of EBVaGC cells. Thus, we wanted to use system of NPC clinical trials to EBVaGC. Targeted EBV antigens expressed both in NPC and EBVaGC were latent membrane proteins (LMPs)-1,2 and EBV-determined nuclear antigen (EBNA) 1. To generate EBV-specific cytotoxic T lymphocytes (EBV-CTLs), we firstly isolated peripheral blood mononuclear cells (PBMCs) from healthy human donor blood by using Ficoll and sorted dendritic cells (DCs) to deliver LMP2A and EBNA1 expressing-vectors by nucleofection into DCs. Nucleofected DCs were cocultured with PBMCs in order to cross-present EBV antigens toward CD4+, CD8+ T cells in DC maturation condition. Generated EBV-CTLs were incubated with IL-2, 7, 15-supplemented CTL media for inducing memory-like cells and expanded for 14 days to apply to adoptive transfer of EBVaGC model. Cytotoxicity of EBV-CTLs were specific for EBV-expressing gastric cancer cell line (SNU 719) in vitro, not EBV-negative gastric cancer cell line (MKN45). To confirm efficacy of EBV-CTLs in mouse model, we developed EBVaGC mouse model using SNU719 and injected 1 × 107 cells/mouse once a week for three times. EBV-CTLs had an effect on the reduction of tumor size of EBVaGC and effectively migrated into tumor site. Also, administered EBV-CTLs stably existed in blood and tumor tissue even over 3 days analyzed by FACS and immunohistochemistry. In conclusion, EBV-CTLs represented improved anti-tumor activity to treat EBVaGC and specific lysis to EBV-expressing cells. Also, any side effects or autoimmune diseases were not detected. Therefore, EBV-CTLs would be likely to play important roles in targeting many EBV-associated cancers and be applied to clinical trials.
Note: This abstract was not presented at the conference.
Citation Format: Jae Seung Moon, Jung Ho Kim, Sang Kyou Lee. Immunotherapy of EBV associated gastric cancer using EBV specific T cells [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B049.