B7-H4 is over-expressed in early-stage ovarian cancer and is independent of CA125 expression

OBJECTIVE: This study characterizes the expression of the novel biomarker B7-H4 in ovarian cancer tissue, normal ovaries, and benign ovarian tumors, and evaluates its relationship to CA125. METHODS: Ovarian tissue lysates from 251 patients with ovarian carcinoma were assessed for the levels of B7-H4 and CA125 by ELISA assays. For comparison, ovarian tissues from patients with benign ovarian tumors (n=43) and patients with normal ovaries (n=32) were tested. The marker concentrations were correlated with CA125 expression, clinicopathological variables, and patient outcome. RESULTS: Using a cut-off based on the 95th percentile of B7-H4 or CA125 concentration in the control group, B7-H4 was over-expressed in 48% of patients with stage I cancer, 55% of patients with stage II cancer, and 67% of patients with late stage cancer. CA125 was elevated in 31% patients with early stage cancer. B7-H4 was elevated in tumors of 30 patients with early stage cancer that were negative for CA125. The combination of B7-H4 and CA125 identified 56 early stage cancer patients (65%) as positive. Correlation of marker expression to clinical outcome showed that high B7-H4 levels were correlated with poor prognosis. However, the effect was not significant when outcome was adjusted for other clinicopathological variables. CONCLUSION: B7-H4 expression was low in normal ovaries and in benign tumors while half of early stage and two-thirds of late stage cancers over-expressed B7-H4. The data are consistent with previous observations and support further investigation of B7-H4 in the detection of early stage ovarian cancer either alone, or in combination with CA125.