T-cell–inflamed gene expression profile (GEP) and PD-L1 expression in patients (pts) with esophageal cancer (EC).

Abstract

26 Background: GEP and PD-L1 expression have been associated with anti–PD-1/PD-L1 therapy. In this retrospective observational study we explored the prognostic value of GEP and PD-L1 expression in pts with EC receiving standard-of-care therapy (SOC). Methods: Tumor tissue samples collected from 2005 to 2017 were procured from Yonsei Cancer Center (South Korea), Memorial Sloan Kettering Cancer Center (USA) and Aarhus University Hospital (Denmark). GEP score was derived from an 18-gene signature using extracted tumor RNA analyzed by NanoString nCounter; GEP high/intermediate (GEP-H/I) and low were defined by a cutoff of –1.540, consistent with pembrolizumab clinical trials. PD-L1 expression was assessed by PD-L1 IHC 22C3 pharmDx assay (Agilent); positive was defined as combined positive score (CPS) ≥ 10, where CPS is the the number of PD-L1–positive cells (tumor cells, lymphocytes and macrophages) divided by the total number of viable tumor cells, multiplied by 100. Associations of GEP score and PD-L1 expression with clinicopathologic variables were analyzed by chi-square test and multiple logistic regression models. Overall survival (OS) from diagnosis date to death date/last follow-up was analyzed using Cox proportional hazards models adjusting for age, sex, stage, region and ECOG performance status (PS). Results: 294 samples with both PD-L1 and GEP data were analyzed. Median age was 65 y (range 33-88); 85% were from men, 58% were stage IV, 63% were esophageal adenocarcinoma (EAC) and 37% were esophageal squamous cell carcinoma (ESCC). Overall 36% of tumors were GEP-H/I: 46% in EAC vs 18% in ESCC. GEP was not associated with OS overall (adjusted hazard ratio [aHR] –0.90; 95% CI 0.68-1.18) or in pts with EAC (aHR 0.93; 95% CI 0.68-1.27) or ESCC (aHR 0.76; 95% CI 0.40-1.44). 21% of tumors were PD-L1-CPS ≥ 10: 18% in EAC and 26% in ESCC. PD-L1 expression was associated with ECOG PS (adjusted odds ratio 0.520; 95% CI 0.309-0.875; P = 0.014) but was not associated with OS overall (aHR 0.89; 95% CI 0.64-1.24) or in pts with EAC (aHR 0.97; 95% CI 0.63-1.49) or ESCC (aHR 1.31; 95% CI 0.73-2.34). Conclusions: Our results suggest that T-cell–inflamed GEP and PD-L1 expression may not be prognostic in pts with EC who received SOC.