Abstract 6465: Clinicopathological features of TROP-2 and pTROP-2 in gastric cancer

Abstract Introduction: The human trophoblast cell-surface antigen TROP-2 is a cell surface glycoprotein receptor involved in tight junctions at the epithelial barrier. Although TROP-2 is reportedly overexpressed in various epithelial tumors and its expression correlates with aggressive tumor behavior, there is no report of the clinicopathological features of gastric cancer (GC) with TROP-2 and phosphorylated TROP-2 (pTROP-2) expression. We evaluated the clinicopathologic significance of TROP-2 and pTROP-2 expression in GC patients. Materials and methods: We retrospectively analyzed the cases of 720 GC patients who underwent resection for GC. The expressions of TROP-2 and pTROP-2 in each tumor were evaluated by immunohistochemistry. We then divided the patients into the TROP-2 high group, TROP-2 low group, pTROP-2 high group, and pTROP-2 low group. The association between TROP-2 or pTROP-2 expression and clinicopathological variables were assessed by the chi-square test. Overall survival was analyzed by Kaplan-Meier method, and compared by log-rank test. The Cox proportional hazards model was used for multivariate analysis. Results: TROP-2 high group was found to be overexpressed in 330 (46.7%) tumor samples. Significantly higher expression of TROP-2 was significantly correlated with intestinal type, tumor invasion depth, lymph node metastasis, lymphatic invasion, and venous invasion. pTROP-2 high group was found to be overexpressed in 306 (43.4%) tumor samples. Significantly higher expression of pTROP-2 was correlated with intestinal type, low tumor invasion depth, no lymph node metastasis, and no lymphatic invasion. TROP2 overexpression was predictive for poor overall survival of patients with GC (p = 0.0002, log rank test), while multivariate analysis to overall survival revealed that TROP-2 overexpression was not an independent prognostic marker (p=0.06). In contrast, pTROP-2 overexpression was predictive for good overall survival of patients with GC (p = 0.004, log rank test). Conclusion: TROP-2 might be associated with metastatic ability of gastric cancer cells, resulting poor prognosis of patients with GC. Citation Format: Syuhei Kushiyama, Masakazu Yashiro, Sadaaki Nishimura, Shingo Togano, Kanji Kuroda, Atsushi Sugimoto, Tomohiro Sera, Yurie Yamamoto, Tomohisa Okuno, Yuichiro Miki, Hiroshi Nakada, Masaichi Ohira. Clinicopathological features of TROP-2 and pTROP-2 in gastric cancer [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 6465.