Serum levels and biochemical characteristics of human ovarian carcinoma-associated antigen defined by murine monoclonal antibody, CF511

The murine monoclonal antibody (Mab) against human common epithelial ovarian carcinoma, CF511, was generated by immunising mice with human fetal tissue extract from early first trimester, followed by booster injection of an ovarian cancer cell line. Mab CF511 recognised the 600 kDa sialylated glycoprotein as different from previously known tumour associated-marker antigens. Distribution of the Mab CF511-recognised antigen (CF511 antigen) in various tissues and sera was investigated. In immunohistochemical analysis, Mab CF511 reacted strongly with tumour cells of ovarian serous, clear cell, endometrioid and undifferentiated carcinoma and partially with those of mucinous carcinoma. Mab CF511 also reacted with breast carcinoma as well as lung carcinoma. In normal tissues, Mab CF511 cross-reacted with only five tissues, namely lung, breast, thyroid gland, fallopian tube and uterus. Serum levels of CF511 antigen were tested by ELISA inhibition using Mab CF511. This assay showed the circulating CF511 antigen levels to be elevated in 25 of 36 sera from patients with various clinical stages of common epithelial ovarian carcinoma compared to three of 47 and three of 111 sera from patients with other benign gynaecological diseases, including ovarian cysts, uterine fibroids with or without endometriosis and normal healthy subjects, respectively. For the relation between antigen levels and clinical stages of common epithelial ovarian carcinoma, greater than 34.0% ELISA inhibition was detected in 100% of patients with advanced stages (FIGO III and IV) compared with in 35.3% with early stages (FIGO I and II) patients. While patients with breast carcinoma (100%) and lung carcinoma (100%) also had elevated circulating CF511 antigen levels, patients with hepatoma, colorectal carcinoma and gastric carcinoma had no detectable elevation of antigen. Although the test showed a high degree of specificity, the detection of an elevated CF511 antigen level would not be so helpful in distinguishing patients with ovarian carcinoma from those with either breast carcinoma or lung carcinoma. These data suggest that CF511 antigen is a useful new ovarian tumour marker for diagnosis and management of the disease.