Studies on an oncofetal antigen, POA.

This paper describes the purification and partial characteristics of a putative oncofetal antigen, POA, which appears to be associated with the pancreas. POA is a glycoprotein of molecular weight between 800,000 and 900,000 daltons. It is found in fetal pancreas and pancreas cancer tissue, but not in normal adult pancreas. It is clearly different from carcinoembryonic antigen, other known tumor associated antigens, acute phase reactants and normal serum proteins. A quantitative rocket immunoelectrophoresis assay was developed for POA. Its specificity was monitored routinely by double immunodiffusion against known fetal and adult standards. The assay was performed on sera from over 700 patients. The results demonstrate that POA is found in the sera of most individuals. However, by far the highest absolute levels and the highest frequency of elevated levels was found in sera of patients with carcinoma of the pancreas. Elevated levels of POA were also found in the serum of a proportion of patients with carcinomas of the lung, stomach, colon, biliary tract, and breast and in a few other individuals with benign conditions. The spectrum of patients who have elevated levels of POA in their serum is quite different from that found with CEA or other known tumor markers.