Clinical significance of CD8 positive tumor-infiltrating lymphocytes density and programmed-death receptor ligand 1 expression in rectal cancer after neoadjuvant chemoradiotherapy / 肿瘤研究与临床

ABSTRACT

Objective:To investigate the correlation of CD8 positive tumor-infiltrating lymphocytes (CD8 + TIL) density and programmed-death receptor ligand 1 (PD-L1) expression in rectal cancer with clinicopathological characteristics and prognosis of patients after neoadjuvant chemoradiotherapy. Methods:The clinicopathological data of 166 patients with locally advanced rectal cancer (LARC) who received neoadjuvant therapy before surgery in the Beijing Chao-Yang Hospital, Capital Medical University from January 2015 to December 2018 were retrospectively analyzed. CD8 + TIL density and PD-L1 expression were detected by using immunohistochemistry. The correlation of CD8 + TIL density and PD-L1 expression with clinicopathological characteristics of patients after neoadjuvant chemoradiotherapy was analyzed. Kaplan-Meier method was used to analyze the disease-free survival (DFS) and Cox regression risk model was used to make univariate and multivariate analysis of the influencing factors for DFS. Results:Among 166 LARC patients, 81 cases (48.8%) had high density of CD8 + TIL, 85 cases (51.2%) had low density of CD8 + TIL; 63 cases (38.0%) had PD-L1 expression, and 103 cases (62.0%) had non-expression of CD8 + TIL. The expression rate of PD-L1 in CD8 + TIL high density group was higher than that in CD8 + TIL low density group [50.6% (41/81) vs. 25.9%(22/85), χ2 = 10.78, P < 0.001]. According to the density of CD8 + TIL and PD-L1 expression, immunophenotype was divided among 4 groups; the 3-year DFS rate of the CD8 + TIL high density /PD-L1 expression group was 87.1%, which was higher than that of the other groups (CD8 + TIL low density /PD-L1 expression group was 72.8%, CD8 + TIL high density /PD-L1 non-expression group was 67.0%, CD8 + TIL low density /PD-L1 non-expression group was 64.3%), and the difference was statistically significant ( P < 0.05). Univariate analysis showed that tumor differentiation degree, TNM stage, CD8 + TIL density, PD-L1 expression and CD8 + TIL density /PD-L1 expression were correlated with the DFS of patients (all P < 0.05). Multivariate analysis results showed that CD8 + TIL high density /PD-L1 expression was an independent protective factor for DFS ( HR = 0.049, 95% CI 0.005-0.497, P = 0.011), while TNM stage 3 was an independent risk factor for DFS ( HR = 2.752,95% CI 1.300-5.825, P = 0.008). Conclusions:In LARC after neoadjuvant therapy, CD8 + TIL density is positively correlated with the expression of PD-L1, and the high density of CD8 + TIL/PD-L1 expression is an independent influencing factor for good prognosis, suggesting that these patients may benefit from the immunotherapy.