Current evaluation of the tissue localization and diagnostic utility of prostate specific membrane antigen

BACKGROUND Current statistics indicate that prostate carcinoma is the most common form of cancer diagnosed in American men, resulting in the second highest cancer death rate. Early diagnosis and accurate staging are imperative given that there is little effective treatment for metastatic disease, especially after androgen deprivation therapy fails. Identification of new biochemical markers for disease progression will provide important tools for diagnosis and monitoring. One such potential marker is prostate specific membrane antigen (PSMA). METHODS A review was conducted to identify reports concerning evaluation of diagnostic applications of PSMA. RESULTS PSMA is a membrane-bound glycoprotein that is highly restricted to the prostate. Immunohistochemical findings indicate that PSMA is a marker of epithelial cells of the prostate. This expression is increased in association with prostate carcinoma, particularly in hormone-refractory disease. Given its membrane-bound character, PSMA has been exploited as a marker for tumor detection by immunoscintiscanning with the 111In-labeled anti-PSMA monoclonal antibody 7E11.C5. Increased concentrations of 7E11.C5-reactive antigen are present in the serum of prostate carcinoma patients compared with healthy individuals; also, hematogenous circulating prostate carcinoma cells are detectable with reverse transcriptase-polymerase chain reaction analysis with primers specific for PSMA. New monoclonal antibodies specific for extracellular portions of the PSMA molecule currently are being utilized in applied studies. CONCLUSIONS PSMA is a widely used marker for prostate epithelial cells. Its up-regulation in association with cancer, particularly in advanced cancer, is ideal for application as a prognostic marker. A variety of promising clinical applications utilizing PSMA have been or are being developed. In the future, these promise to have an important impact on cancer diagnosis and patient treatment. Cancer 1998;83:2259-2269. © 1998 American Cancer Society.