Monoclonal antibody PR92 with restricted specificity for tumor-associated antigen of prostate and breast carcinoma.

A unique mouse hybridoma, PR92, was obtained using human prostate adenocarcinoma cell line DU145. The monoclonal antibody produced by the PR92 clone was reactive with DU145, MCF-7 (breast adenocarcinoma), and CHAGO (lung carcinoma), but not with normal cell lines and 16 other cell lines of cancerous origin. A homologous solid-phase sandwich radioimmunoassay (PR92-RIA) was developed utilizing PR92 monoclonal antibody. The PR92-RIA recognized unique antigen present in DU145 cell extract but did not detect 16 other known tumor-associated markers. In preliminary studies, the PR92-RIA measured greater than 5 units/ml level of PR92 monoclonal antibody-binding antigen in 23 of 31 (74%) serum specimens of active prostate cancer and 27 of 31 (87%) active breast carcinoma patients. Only 1 of 79 (1%) sex-matched normal donors and 1 of 57 (2%) benign disease control patients showed the serum antigen level greater than 5 units/ml. A high degree of correlation was observed between the PR92 antigen activity and the clinical status of four prostate and four breast cancer patients during therapeutic treatment. Thus, the PR92-RIA detects new tumor-associated antigen which may be useful in detection and monitoring of prostate and breast carcinoma patients.