PD-1 and PD-L1 Protein Expression Predict Survival in Completely Resected Lung Adenocarcinoma

The prognostic value of programmed cell death 1 (PD-1) and/or programmed cell death ligand 1 (PD-L1) expression in completely resected lung adenocarcinoma is still unclear. The expression of PD-1 and PD-L1 was determined using immunohistochemistry in 161 patients with lung adenocarcinoma. PD-1 and PD-L1 expression was associated with favorable overall survival. This knowledge could be important in the design of future clinical trials evaluating immune checkpoint inhibitors. Background: We assessed the prognostic value of programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) in patients with completely resected lung adenocarcinoma. Patients and Methods: PD-1 and PD-L1 expression was determined using immunohistochemistry in formalin-fixed paraffin-embedded surgical specimens and correlated with the clinicopathologic features and survival of 161 patients with lung adenocarcinoma. Results: PD-1 expression on immune cells was observed in 71 of 159 evaluable tumor samples (45%) and was not significantly associated with the clinicopathologic features. Multivariate analyses identified PD-1 expression as an independent prognostic factor for recurrence (adjusted hazard ratio [HR], 0.59; 95% confidence interval [CI], 0.36-0.95; P = .03) and death (adjusted HR, 0.48; 95% CI, 0.27-0.86; P = 0.01). PD-L1 expression on tumor cells was seen in 59 of 161 cases (37%) and correlated with KRAS mutation status (P = .02) and type of surgery (P = .01). PD-L1 expression was not associated with recurrence-free survival in the patients (adjusted HR, 0.90; 95% CI, 0.55-1.48; P = .68) but correlated with longer overall survival (adjusted HR, 0.54; 95% CI, 0.30-0.97; P = .04). Conclusion: PD-1 and PD-L1 expression was associated with favorable overall survival in patients with completely resected adenocarcinoma of the lung. (C) 2018 Elsevier Inc. All rights reserved.