Serum soluble B7-H3 is a prognostic marker for patients with non-muscle-invasive bladder cancer

Background B7-H3 is a member of the B7 family of immune-regulatory ligands and is a costimulatory molecule promoting the T cell response in vitro. We herein investigated the clinical utility of serum soluble B7-H3 (sB7-H3) in patients with non-muscle invasive bladder cancer (NMIBC). Methods We analyzed 555 patients in whom NMIBC was diagnosed at Tokyo Metropolitan Tama Medical Center between 2008 and 2013. We measured the serum sB7-H3 (sB7-H3) level using the enzyme-linked immunosorbent assay (ELISA) and evaluated the utility of sB7-H3 as a prognostic biomarker for NMIBC. We used the Cox proportional hazards regression model to assess recurrence-free survival (RFS) and progression-free survival (PFS) with the sB7-H3 level. Results We detected high levels of sB7-H3 in the sera of 47% of patients with NMIBC versus only 8% in healthy donors. The increase of sB7-H3 was significantly associated with poor RFS and PFS. Multivariate analysis showed that elevated sB7-H3 was an independent prognostic factor of RFS and PFS. According to the European Organization for Research and Treatment of Cancer (EORTC), in intermediate-low and intermediate-high risk groups, the presence of sB7-H3 significantly determined the rate of recurrence and progression. Conclusions Our data suggested that evaluating serum sB7-H3 expression is a useful tool for predicting the prognosis of patients with NMIBC.