Positive Programmed Cell Death-Ligand 1 Expression Predicts Poor Treatment Outcomes in Esophageal Squamous Cell Carcinoma Patients Receiving Neoadjuvant Chemoradiotherapy

Background: Programmed cell death-ligand 1 (PD-L1) is present in a subgroup of cancer patients who may be favorable targets for immune checkpoint inhibitor therapies. However, the significance of the PD-L1 expression in esophageal squamous cell carcinoma (ESCC) patients receiving neoadjuvant chemoradiotherapy remains unclear. Methods: By means of PD-L1 immunohistochemistry 22C3 pharmDx assay, we evaluate the PD-L1 expression and its association with clinical outcome in 107 ESCC patients receiving neoadjuvant chemoradiotherapy. Results: Patients with positive PD-L1 expression have significantly lower pathological complete response rates (13% versus 32%; P = 0.036) than those with negative PD-L1 expression. Univariate survival analysis found that positive PD-L1 expression were correlated with poor overall survival (P = 0.004) and inferior disease-free survival (P < 0.001). In a multivariate analysis, positive PD-L1 expression was independently associated with the absence of a pathologically complete response (P = 0.044, hazard ratio: 3.542), worse overall survival (P = 0.006, hazard ratio: 2.017), and inferior disease-free survival (P < 0.001, hazard ratio: 2.516). Conclusions: For patients with ESCC receiving neoadjuvant chemoradiotherapy, positive PD-L1 expression independently predicts the poor chemoradiotherapy response and worse treatment outcome. Thus, our data suggests that PD-L1 may be an influential biomarker for prognostic classification and for immune checkpoint inhibitor therapies in ESCC patients receiving neoadjuvant chemoradiotherapy