Abstract 2370: Elevated levels of anti-Epstein Barr virus (EBV) antibodies in EBV-associated gastric carcinoma
Authors: Song Lusheng , Song Minkyo , Camargo M. Constanza , Van Duine Jennifer , Williams Stacy , Chung Yunro , Kim Kyoung-Mee , Lissowska Jolanta , Isajevs Sergejs , Kim Sung , Gao Weimin , Karthikeyan Kailash , Park Jin , Leja Marcis , Cohen Jeffrey L. , LaBaer Joshua , Qiu Ji , Rabkin Charles S. 
Published: September 2020

Abstract
Background: Almost 10% of gastric carcinomas contain Epstein-Barr virus (EBV) DNA, which is not found in other gastrointestinal tract cancers. EBV-positive tumors have distinct clinico-epidemiologic features and are molecularly characterized by recurrent PIK3CA and absent TP53 mutations, JAK2 and PD-L1/L2 amplifications, and extreme DNA hypermethylation. Identification of the gastric cancer-specific antibody response to this common infection may elucidate its contribution to carcinogenesis and provide a non-invasive method to detect EBV-positive gastric tumors.
Methods: Plasma samples from Latvian patients with EBV-positive (n=28) and -negative (n=34) gastric cancer were immune-profiled against 85 EBV proteins expressed in situ on a multi-microbiome Nucleic Acid Programmable Protein Array (NAPPA). Antibody responses were normalized as ratios to the median signal intensity across all antigens, with seropositivity defined as ratios ≥ 2. Antibodies with ≥ 20% sensitivity at 95% specificity for EBV status were verified by enzyme-linked immunosorbent assay (ELISA) and then validated in independent samples from Korea and Poland (n=24 EBV-positive, n=65 EBV-negative).
Results: Forty anti-EBV IgG and eight IgA antibodies were present by NAPPA in ≥ 10% of EBV-positive or EBV-negative gastric cancer patients, of which nine were sensitive and specific for tumor EBV status. Eight of these nine were verified and seven were validated by ELISA: anti-LF2 (odds ratio=110.0, p&lt;0.01), anti-BORF2 (54.2, p&lt;0.01), anti-BALF2 (44.1, p&lt;0.01), anti-BaRF1 (26.7, p&lt;0.01), anti-BXLF1 (12.8, p=0.01), anti-BRLF1 (8.3, p&lt;0.01), and anti-BLLF3 (5.4, p=0.02). The top three antibodies had areas under the receiver operating characteristics curve of 0.81-0.85 for discriminating gastric cancer EBV status.
Conclusions: This is the first comprehensive immune profiling of anti-EBV response in gastric cancer. Despite the ubiquity of EBV infection in adults, seven novel anti-EBV antibodies were identified and validated to distinguish viral involvement in gastric cancer. Unlike other major EBV-associated malignancies such as nasopharyngeal carcinoma and lymphoma, the gastric cancer-specific humoral response is exclusively directed against lytic cycle immediate-early and early antigens. EBV serology could have utility for clinical diagnosis, epidemiologic studies, and precision treatment of EBV-positive gastric cancer.
Citation Format: Lusheng Song, Minkyo Song, M. Constanza Camargo, Jennifer Van Duine, Stacy Williams, Yunro Chung, Kyoung-Mee Kim, Jolanta Lissowska, Sergejs Isajevs, Sung Kim, Weimin Gao, Kailash Karthikeyan, Jin Park, Marcis Leja, Jeffrey L. Cohen, Joshua LaBaer, Ji Qiu, Charles S. Rabkin. Elevated levels of anti-Epstein Barr virus (EBV) antibodies in EBV-associated gastric carcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2370.