Serologic analysis of ovarian tumor antigens reveals a bias toward antigens encoded on 17q

We utilized SEREX immunoscreening to identify a set of novel tumor antigens that are associated with human serous ovarian cancer and may prove useful for the early detection and treatment of this disease. Extensive screening with a panel of sera from 25 late-stage ovarian cancer patients against 3 independent cDNA libraries identified a set of 9 antigens that were immunogenic in more than 1 patient and not in a panel of 20-45 normal female serum donors. These antigens include p53, NY-ESO-1, UBQLN1, HOXB6, TOP2A, putative helicase-RUVBL (RUVBL), HMBA-inducible (HEXIM1), DDX5 and HDCMA. Ten of 25 ovarian cancer patients (40%) expressed serum IgG to at least 1 of these antigens, while 14% (4/25) had antibodies to 2 or more antigens. Unexpectedly, 4 antigens identified in this screen, DDX5, HEXIM1, TOP2A and HOXB6, are encoded within a region of 17q that also includes the genes for HER2/neu, Homeobox-B7 and BRCA1. Real-time RT-PCR analysis showed that mRNA for HER2/neu and 3 SEREX-defined antigens, TOP2A, HOXB6 and DDX5, was more abundant in ovarian tumors than most normal tissues, including normal and benign ovarian tissues, suggesting that elevated expression of genes encoded within this region of chromosome 17 is a common event in ovarian tumors. Thus, these abnormal expression patterns combined with the endogenous immune response suggests that these antigens represent potential targets for immunotherapy.