Comparative study of the tumor-infiltrating lymphocytes before and after neoadjuvant chemoimmunotherapy in esophageal squamous cell carcinoma

BACKGROUND: OBJECTIVE: To explore changes of tumor-infiltrating lymphocytes and the relationship with therapeutic effect before and after neoadjuvant chemoimmunotherapy in patients with esophageal squamous cell carcinoma(ESCC). METHOD: This study collected clinical data from 25 ESCC patients with neoadjuvant chemoimmunotherapy from November 2019 to June 2022 in our hospital. After the completion of the neoadjuvant treatment, Mckeown MIE surgery was performed. The pathological specimen before therapy and after surgery was collected. Immunohistochemical analysis was performed to obtain the tumor-infiltrating lymphocytes (TILs) infiltration of the tumor before and after treatment. RESULT: Seven (28%) patients achieved pathology complete response (pCR group) and 18 (72%) patients did not achieve pCR (non-pCR group). Compared with non-pCR group, the after treatment proportion of CD4 + TILs (P = 0.012) and the proportion of CD8 + TILs (P = 0.018) were significantly increased in pCR group; There was no significant change in the proportion of CD20 + TILs (Z = -1.933, P = 0.053). In pCR group, the proportion of CD4 + TILs (P = 0.047) and the proportion of CD8 + TILs (P = 0.036) were significantly increased after treatment; The proportion of CD20 + TILs (P = 0.111) did not change significantly. In non-pCR group, no significant changes were observed in proportions of CD4 + TILs (P = 0.729), CD8 + TILs (P = 0.712), and CD20 + TILs (P = 0.811) between before and after treatment. CONCLUSION: For ESCC patients who received neoadjuvant chemoimmunotherapy, patients with pCR had a more active immune response independent of pre-treatment PD-L1 expression levels, and the pre-treatment CD4 + TILs ratio may be one of the predictors of their survival.