Tumor immune microenvironment remodeling and prognosis of patients with esophageal squamous cell carcinoma after neoadjuvant chemotherapy with and without immunotherapy: a retrospective cohort study

Background: Immunochemotherapy was an emerging neoadjuvant treatment mode that can potentially benefit patients with esophageal carcinoma, but its synergistic mechanism and impact on the tumor immune microenvironment were still unclear. The purpose of this study was to investigate the outcomes of neoadjuvant chemotherapy (nCT) and neoadjuvant immunochemotherapy (nICT) in tumor microenvironment (TME) remodeling among patients with esophageal squamous cell carcinoma (ESCC) and to evaluate the prognostic value of immune-related biomarkers and clinicopathological characteristics. Methods: Patients with locally advanced ESCC who underwent neoadjuvant therapy followed by esophagectomy at the Fourth Hospital of Hebei Medical University between December 2019 and March 2022 were enrolled in this retrospective study. We examined TME features and immune antigen-related biomarkers before and after neoadjuvant therapy. Logistic and Cox regression model were used to evaluate the correlation between these factors and other clinical features and outcomes. Results: A total of 50 eligible participants were analyzed, including 31 males (62%), 25 patients of >= 65 years old, 4/28/18 of upper/middle/lower thoracic cancer, 25/17/8 of poor/moderate/high tumor differentiation, 8/42 of cT1+2/T3+4 stages and 30/20 of cN0/N+ stages. In the entire cohort, the rates of pathological complete response (pCR) and major pathological response (MPR) were 18% and 30%, respectively. pCR rates were 7.1% and 22.2% (chi(2)=0.699; 2 =0.699; P=0.40) MPR rates were 7.1% and 38.9% (chi(2)=4.837; 2 =4.837; P=0.03) in the nCT and nICT groups, respectively. Compared with the non-pCR patients, the pCR patients had a higher baseline programmed cell death ligand-1 (PD-L1) tumor proportion score (TPS) positive expression rate (16.7% vs. 77.8%, chi(2)=13.089; 2 =13.089; P<0.001). Following neoadjuvant therapy, the expression rates of PD-L1, CD3+T + T cells, and CD8+ + T cells in the tumor tissue was higher in the nICT group compared to the nCT group (P<0.05). Deficient expression of mismatch repair (MMR) genes was only observed in one patient (2%). Among patient-related biomarkers, lymphocyte and neutrophil counts decreased after treatment, with no significant changes in the neutrophil-to-lymphocyte ratio or platelet-to-lymphocyte ratio (PLR). Cox regression analysis showed that pretreatment, well-differentiated tumors and positive PD-L1 status were positive predictors of MPR (P<0.05). MPR was an independent predictor of disease-free survival (DFS) (P=0.03). Conclusions: Compared to nCT, nICT could more significantly upregulates PD-L1 TPS, PD-L1 combined positive score (CPS), CD3(+) T cells, and CD8(+) T cells. Pretreatment tumor differentiation and PD- L1 TPS level could be predictive of MPR. Our findings suggested that the combination of chemotherapy and immunotherapy may be more beneficial for activating anti-tumor immunity in the TME.