Prognostic impact of programmed death-ligand 1 expression in correlation with human leukocyte antigen class I expression status in stage I adenocarcinoma of the lung.

OBJECTIVE: The study objective was to investigate the prognostic impact of programmed death-ligand 1 expression in correlation with human leukocyte antigen class I expression on tumor cells in early-stage adenocarcinoma of the lung, because both programmed death-ligand 1 and human leukocyte antigen class I molecules play important roles in cancer immunity.

METHODS: Ninety-four patients with completely resected pathologic stage I lung adenocarcinoma were retrospectively reviewed. Programmed death-ligand 1 expression on tumor cells was evaluated with immunohistochemistry in correlation with several clinicopathologic and molecular features, including human leukocyte antigen class I expression on tumor cells.

RESULTS: Fifteen patients (16.0%) had tumor with positive programmed death-ligand 1 expression (percentage of tumor cells expressing programmed death-ligand 1, ≥5%), and the incidence was significantly higher in poorly differentiated tumors. There was no significant correlation between human leukocyte antigen class I expression and programmed death-ligand 1 expression. Programmed death-ligand 1 positivity was a significant factor to predict a poor survival (5-year survival, 66.7% vs 85.9%; P = .049), which was enhanced in tumors with normal human leukocyte antigen class I expression (P = .029) but was not evident in tumors with reduced human leukocyte antigen class I expression (P = .552).

CONCLUSIONS: The prognostic impact of programmed death-ligand 1 expression on tumor cells in early-stage lung adenocarcinoma may be distinct according to concurrent human leukocyte antigen class I expression.