Impact of the combination of sintilimab and chemotherapy on the tumor and paratumor PD‐L1, IDO, TIM‐3, FOXP3+ and CD8 expressions in patients with advanced esophageal squamous cell carcinoma

BACKGROUND: Anti‐PD‐1/PD‐L1 therapeutics have been widely used in the clinic in various tumors, including advanced esophageal cancer, showing remarkable treatment efficacy. Factors determining the response to anti‐PD‐1/PD‐L1 therapeutics are numerous, including the tumor microenvironment, such as CD8+ T cells and expression of PD‐1/PD‐L1. Our study aimed to explore the effect of chemoimmunotherapy on the expression of CD8+ T cells, TIM‐3, and FOXP3+ in tumor, paratumor tissues, and the expression of PD‐L1, IDO, in tumor, paratumor tissues, and lymph nodes, and analyze the correlation among these markers. METHODS: A total of 18 patients were allocated into two treatment groups: a treatment group and a concurrent control group. A total of 38 tissue samples, 114 slides (tumor, paratumor, and lymph node) were collected in the treatment group, and 37 tissue samples, 111 slides (tumor, paratumor, and lymph node) were collected in the concurrent control group. RESULTS: The expression of PD‐L1, CD8+, FOXP3+, TIM‐3, and IDO in tumors, paratumor tissues, but not lymph nodes, was significantly affected by chemoimmunotherapy. Compared with patients without chemoimmunotherapy, the expression of CD8+ T cells, IDO, and PD‐L1 was significantly decreased in tumor and paratumor tissues after chemoimmunotherapy, while FOXP3+ expression was significantly decreased only in tumor tissues, and TIM‐3 expression was significantly decreased only in paratumor tissues. Moreover, the correlation between these markers was also completely altered after chemoimmunotherapy. In addition, N staging was associated with high expression of CD8 in advanced esophageal squamous cell carcinoma in the concurrent control group. CONCLUSION: This study provides new insight into the effects of CI treatment on isolated CD8+ T cell infiltration, PD‐L1, IDO, FOXP3+ and TIM‐3 expression as well as their cross‐talk in different tissues enabling a better understanding of the impact of CI treatment on the immune microenvironment.