CD155 expression and its clinical significance in non-small cell lung cancer

CD155 serves an important role in tumor progression by promoting cell proliferation and migration. CD155 is also involved in the immune evasion of tumor cells, which may cause the development and progression of tumors. Accordingly, CD155 has emerged as a novel target in cancer immunotherapy; however, its expression in lung cancer remains unclear. To assess CD155 expression and its prognostic significance, 96 patients with completely resected pathologic stage I adenocarcinoma of the lung were retrospectively reviewed. Immunohistochemical staining was performed to evaluate CD155 expression on tumor cells. Expression levels of programmed death-ligand 1 (PD-L1), another molecule participating in immune evasion, were also evaluated immunohistochemically. CD155 expression was positive in 37 patients (38.5%). CD155-positivity was associated with aggressive tumor behavior, such as pleural invasion and vascular invasion. In addition, CD155-positivity was a significant factor to predict a poor prognosis (5-year overall survival (OS) rate, 63.3% for CD155-positive patients vs. 93.1% for CD155-negative patients; P<0.001). Patients harboring tumors with positive CD155 and PD-L1 expression showed the poorest prognosis (5-year OS rate, 44.4% for both-positive patients vs. 85.4% for the other patients; P<0.001). The positive expression status of both CD155 and PD-L1 was a significant and independent unfavorable prognostic factor (hazard ratio, 3.86; 95% confidence interval, 1.51-9.89; P=0.004; in a multivariate analysis). In conclusion, CD155-positivity was associated with aggressive tumor behavior, and was a factor to predict a poor prognosis. Its prognostic impact was enhanced when combined with PD-L1 expression status. These results should be validated in a large-scale study.