Abstract #LB-263: Elevated levels of circulating folate receptor alpha in women with ovarian cancer.

Despite a relatively low incidence rate, ovarian cancer is the fifth leading cause of cancer deaths and it has the highest mortality rate of all gynecologic malignancies among US women. The high mortality rate could potentially be reduced if a marker of early detection were available for routine screening. The folate receptor alpha (FR\#945;) is one seemingly logical choice for a biomarker because of its prevalent overexpression (~95%) in ovarian cancer and its relatively exclusive expression in only a few normal healthy tissues. In a prior recent study, it was observed that patients with ovarian cancer had elevated serum levels of a protein that bound to a FR\#945;-specific monoclonal antibody relative to control healthy individuals. Although it was not shown that the protein detected was definitively FR\#945;, that work did suggest that FR\#945; may be a useful biomarker of ovarian cancer. Thus, in the current study, the goal was to determine whether ovarian cancer patients (n=30) had elevated serum levels of a fully functional intact FR\#945; compared to matched healthy controls (n=30). Circulating FR\#945; levels in serum were analyzed by two methods; 1) immunoprecipitation followed by immunoblotting and semi-quantitative band intensity analysis or 2) a radiolabeled folic acid-based micro-filtration binding assay. Using the immunoassay, we observed that levels of circulating FR\#945; were significantly higher in serum of ovarian cancer patients as compared to matched control subjects (14 ± 8 au vs. 7 ± 5 au, p Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr LB-263.