Clinical Significance of the B7-H4 Coregulatory Molecule as a Novel Prognostic Marker in Gastric Cancer

The B7-H4 coregulatory molecule is a member of the B7 family of molecules, which regulate the T-cell-mediated immune response through CD28 receptors. Recently, B7-H4 has been reported to be a negative regulator of the immune response in patients with several malignant diseases. However, few reports have investigated the clinical significance of B7-H4 expression in patients with gastric cancer. In the present study, we analyzed B7-H4 expression and the relationship between its expression and clinicopathological factors including prognosis in gastric cancer. B7-H4 expression in gastric cancer cell lines and clinical gastric cancer specimens was initially assessed with the reverse transcription-polymerase chain reaction (RT-PCR). Moreover, B7-H4 and CD3 expression in 120 resected specimens from gastric cancer patients were evaluated by immunohistochemistry (IHC). B7-H4 expression was identified in the gastric cancer cell lines and clinical tumor tissues by RT-PCR. B7-H4 expression was high in 25.8% (31/120) of resected tumor specimens. B7-H4 expression significantly correlated with tumor stage (P = 0.04). The 5-year survival rate was significantly lower in patients with high B7-H4 expression than in those with low B7-H4 expression (P = 0.001). Multivariate analysis demonstrated that B7-H4 expression was an independent prognostic factor (P = 0.035). Immunohistochemical analysis of CD3 expression showed that B7-H4 expression was inversely correlated with the number of tumor infiltrating T lymphocytes (P < 0.001). The B7-H4 coregulatory molecule is a novel prognostic marker related to the T-cell-mediated immune response, and its pathway may be a molecular target for controlling tumor progression in patients with gastric cancer.