Neoadjuvant Chemotherapy Increases PD-L1 Expression and CD8+ Tumor-infiltrating Lymphocytes in Esophageal Squamous Cell Carcinoma.

Objective: The aim of this study was to investigate PD-L1 expression and its association with prognosis in esophageal squamous cell carcinoma (ESCC) before and after neoadjuvant chemotherapy (5-fluorouracil and cisplatin, NAC-FP).

Methods: Using a database of 69 ESCC patients, we analyzed PD-L1 expression on tumor cells (TCs) and immune cells (ICs), as well as the density of CD8+ tumor-infiltrating lymphocytes (TILs) in pretreatment biopsy specimens-versus-surgical specimens after resection. We determined the prognostic significance of these factors.

Results: The fraction of ESCC containing ICs expressing PD-L1 and having a high CD8+ TIL density was significantly increased after neoadjuvant treatment. However, PD-L1 expression on TCs or ICs, and CD8+ TIL density, was not significantly associated with patient survival in ESCC patients.

Conclusions: NAC-FP induced PD-L1 expression on ICs and CD8+ TILs in ESCC patients. This finding suggests that PD-1/PD-L1 blockade could be combined with NAC-FP to treat ESCC patients.