Abstract

The WFDC2 (HE4) gene is amplified in ovarian carcinomas, whereas its expression in normal tissues, including ovary, is low. Although the function of the HE4 protein is unknown,it is a member of a family of stable 4-disulfide core proteins that are secreted at high levels. We therefore performed experiments to explore whether quantitation of HE4 protein levels in serum can be used as a biomarker for ovarian carcinoma. A fusion gene was constructed encoding the HE4 protein fused to a gene encoding the murine IgG2a Fc domain. Subsequently, protein produced in mammalian cells was purified by affinity chromatography and used to immunize mice to generate hybridomas specific for HE4. Hybridoma supernatants were screened for binding to a similar fusion protein that, instead, had a human immunoglobulin tail. Two hybridomas, 2H5 and 3D8, were selected that produce monoclonal antibodies to different HE4 epitopes, and a double determinant ("Sandwich") ELISA was constructed and shown to detect a signal at the 160-pg level. Blinded studies on sera from postmenopausal patients with ovarian carcinoma and controls indicate that the specificity and sensitivity of the HE4-based ELISA is equivalent to that of the CA125 assay. However, the HE4 assay may have an advantage over the CA125 assay in that it is less frequently positive in patients with nonmalignant disease.