Abstract 2635: Differential prognostic implications of programmed death-ligand 1 expression on tumor cells and tumor-infiltrating immune cells in patients with locally advanced esophageal squamous cell carcinoma treated with preoperative chemoradiotherapy

Abstract

Abstract Introduction Previous studies have reported inconsistent results on the prognostic implications of program death-ligand 1 (PD-L1) expression for patients with locoregional esophageal squamous cell carcinoma (ESCC). We evaluated the differential prognostic impacts of the PD-L1 expressions on tumor cells and on tumor infiltrating immune cells in a cohort of locally advanced ESCC patients, receiving neoadjuvant chemoradiotherapy (CRT). Patients and Methods A cohort of 66 patients of locally advanced ESCC have been enrolled to a phase II clinical trial of a single-cycle chemotherapy (a combination of weekly paclitaxel, cisplatin and 24 hour infusional 5-fluorouracil, 2 week on plus one week off, followed by paclitaxel/cisplatin (TP) -based preoperative CRT and radical surgery. Primary tumor tissues were retrospectively collected for PD-L1 immunohistochemical stain by the Clone SP142 antibody (Spring Bioscience, Pleasanton, CA, USA). The expression of PD-L1 was scored as previously reported. Tumor cells (TCs) were scored according to percentage of positively-stained cells: TC3≥50%, TC2≥5% and <50%, TC1≥1% and <5%, and TC0<1%; Immune cells (ICs): IC3≥10%, IC2≥5% and <10%, IC1≥1% and <5%, and IC0<1%. Results PD-L1 expression was evaluable on tumor cells in 49 patients and on immune cells in 51 patients. TC0, TC1, TC2, and TC3 were scored in 27 (55%), 9 (18%), 11 (22%), and 2 (4%) patients, respectively; and IC0, IC1, IC2, and IC3 were in 25 (49%), 9 (18%), 15 (29%), and 2 (4%) patients, respectively. Regression analysis revealed that PD-L1 expressions on TC and IC exhibited different impacts on overall survival (OS): higher PD-L1 expression on TC trended to correlate with worse OS, whereas higher PD-L1 expression on IC trended to correlated with better OS. The median OSs of patients with TC0 and those with TC 1-3 were 52 months and 21 months, respectively, with a hazard ratio (HR) 1.5 (95% confidence interval [CI]: 0.7~3.3; P= 0.27). According to the PD-L1 expressions on TC and IC, patients with TC(+)/IC(+), TC(+)/IC(-), TC(-)/IC(+), TC(-)/IC(-) exhibited median OSs of 26, 7, 42, and 43 months, respectively. Patients with TC(+)/IC(-) PD-L1 expression had significantly worse OS than other patients (HR: 2.6, P=0.03). Among patients with TC(+) PD-L1 expression, those with IC(-) had significantly worse OS than those with IC (+), too (HR: 2.5, P=0.04). Conclusion High PD-L1 expression on TC and low PD-L1 expression on IC associate with inferior prognosis in locally advanced ESCC patients treated with neoadjuvant CRT. (The study was supported by the grant NTUH 104-M2891 and the grant MOST 105-2314-B-002-186-MY3) Citation Format: Ta-Chen Huang, Cher-Wei Liang, Chia-Chi Lin, Ya-Jhen Chen, Kuan-Ling Lin, Chih-Hung Hsu. Differential prognostic implications of programmed death-ligand 1 expression on tumor cells and tumor-infiltrating immune cells in patients with locally advanced esophageal squamous cell carcinoma treated with preoperative chemoradiotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2635.