Expression of B7-H4 in blood of patients with gastric cancer predicts tumor progression and prognosis

Background and Objectives: B7-H4 is a novel molecular B7 ligand that plays an important role as a negative regulator of the T cell-mediated immune response. However, the clinical significance of B7-H4 expression in gastric cancer remains uncertain. Here, we assessed B7-H4 expression in blood of patients with gastric cancer to determine whether or not it can predict tumor progression and prognosis. Methods We measured B7-H4 mRNA expression by quantitative RT-PCR in five gastric cell lines as well as in blood specimens from 94 patients with gastric cancer and from 22 healthy volunteers. Results Significantly more B7-H4 mRNA copies were found in gastric cell lines and in blood from patients with gastric cancer than in blood from healthy volunteers (P < 0.0001 and P < 0.0001, respectively). B7-H4 expressed in 71 (75.5%) of 94 patients with gastric cancer significantly correlated with depth of tumor invasion, lymph node metastasis, and overall stage (P = 0.006, P = 0.001, and P < 0.001, respectively). The 5-year survival rate was significantly lower in patients with than without B7-H4 expression (P = 0.04). Conclusions The evaluation of B7-H4 expression in blood is a useful tool for predicting the progression of gastric cancer and prognosis.