B7-H7 is a prognostic biomarker in epithelial ovarian cancer

Background: B7-H7 is a newly identified member of the B7 immune checkpoint family, but has not been investigated in epithelial ovarian cancer (EOC). This study aimed to determine the B7-H7 expression profile and its potential clinical significance in EOC. Methods: A tissue microarray (TMA) containing 160 ovarian cancer tissues was used in this study and 119 EOC cases were valid for analysis. B7-H7 expression was analyzed separately by multiplex immunohistochemistry (mIHC) staining in different compartment according to tissue segmentation. Correlations of B7-H7 expression and pathological characteristics, including overall survival (OS) and disease-free survival (DFS), were explored. Results: Multiplex immunohistochemistry staining showed that B7-H7 was broadly expressed in EOC. B7-H7 expression was significantly higher in the tumor compartment than in stromal compartment of EOC. In EOC tissues, B7-H7 expression in tumor compartment was significantly associated with age (P<0.05); B7-H7 expression in stromal compartment was significantly associated with Federation of Obstetrics and Gynecology (FIGO) stage, lymph nodes metastasis, distant metastasis, and OS (all, P<0.05). The Kaplan-Meier survival analysis revealed that high B7-H7 expression in stromal compartment was significantly correlated with the poor OS of EOC patients (P<0.05), but B7-H7 expression in tumor compartment was not. Conclusions: Stromal B7-H7 expression is significantly associated with tumor progression and prognosis in EOC patients, which might be a prognostic predictor and a potential therapeutic target.