Comprehensive immunohistochemical analysis of tumor microenvironment immune status in esophageal squamous cell carcinoma

// Ken Hatogai 1, 2, 3 , Shigehisa Kitano 4 , Satoshi Fujii 1 , Takashi Kojima 2 , Hiroyuki Daiko 5 , Shogo Nomura 6 , Takayuki Yoshino 2 , Atsushi Ohtsu 2, 7 , Yuichi Takiguchi 3 , Toshihiko Doi 2 , Atsushi Ochiai 1 1 Division of Pathology, Exploratory Oncology Research and Clinical Trial Center, National Cancer Center, Kashiwa, Chiba, Japan 2 Department of Gastroenterology and Gastrointestinal Oncology, National Cancer Center Hospital East, Kashiwa, Chiba, Japan 3 Department of Medical Oncology, Graduate School of Medicine, Chiba University, Chuo-ku, Chiba, Japan 4 Department of Experimental Therapeutics, Exploratory Oncology Research and Clinical Trial Center, National Cancer Center, Tokyo, Japan 5 Department of Esophageal Surgery, National Cancer Center Hospital East, Kashiwa, Chiba, Japan 6 Biostatistics Division, Center for Research Administration and Support, National Cancer Center, Kashiwa, Japan 7 Exploratory Oncology Research and Clinical Trial Center, National Cancer Center, Kashiwa, Japan Correspondence to: Atsushi Ochiai, email: aochiai@east.ncc.go.jp Keywords: esophageal cancer, immunohistochemistry, PD-L1, tumor infiltrating lymphocyte, macrophage Received: December 31, 2015      Accepted: June 04, 2016      Published: June 15, 2016 ABSTRACT Immunotherapy with anti-PD-1 antibody preliminarily showed promising efficacy for treating esophageal squamous cell carcinoma (ESCC). Herein, we used tissue microarrays and immunohistochemically analyzed PD-L1 and various tumor infiltrating immune cells (TIICs) in specimens from 196 ESCC patients who had undergone curative resection without preoperative therapy. PD-L1 expressions in tumor cells (TCs) and TIICs, as well as infiltration of lymphocytes (CD4 + , CD8 + , FOXP3 + , and PD- 1 + ) and macrophages (CD68 + and CD204 + ), were evaluated. PD-L1 was expressed in TCs of 18.4% and in TIICs of 83.3% of these patients. PD-L1 expressions in TCs and TIICs were associated with significant infiltration of various TIIC types, especially CD8 + cells. PD-L1 expressions in both TCs and TIICs were significantly associated with favorable overall survival, and combining their levels enhanced prognostic accuracy. Prognostic impacts of PD-L1 expressions in TCs and TIICs, abundant PD-1 + cell infiltration, a high CD8 + /FOXP3 + ratio, and the CD8 + /CD204 + ratio remained significant after adjusting for clinicopathological factors. In conclusion, PD-L1 expression reflects anti-tumor immunity, and PD-1/PD-L1 expression and the ratio of infiltrating effector to immune suppressor cells have prognostic value. Therapeutic strategies inhibiting the PD-1/PD-L1 signal and immune suppressor cells are anticipated in ESCC patients.