IMMUNODIAGNOSTIC AND THERAPEUTIC MANAGEMENT OF COLON-CANCER USING PROTEIN-DERIVED MONOCLONAL-ANTIBODY-31.1

Antibody 31.1 and 33.28 represent protein monoclonal antibodies derive d from a double banded membrane glycoprotein found in colon cancer and essentially not expressed in normal bowel. The glycoproteins are stro ngly immunogenic and capable of stimulating both cell mediated and hum oral responses. The two antigens defined by the monoclonals, migrate c losely together on electrophoresis and have been shown to have M.W. of 72,000 for antigen 31.1. and 61,100 for antigen 33.28, Studies using immunoperoxidase have suggested that 33.28 is initially expressed in t he early transforming cells and that 31.1 is seen with greater frequen cy in the higher grade tumors. Specificity for both antibodies are hig h, so that in a study of shed coloncytes at the Mayo Clinic, sensitivi ty and specificity were superior when compared with anti-CEA, anti-MUC 1 and B72.3. Of more interest however is the cytolytic activity of mon oclonal 31.1. When compared with murine 17.1A which was found to have clinical benefit by Rietmuller, 31.1. had far more of a response. Muri ne 17.1A showed lysis in approximately 17% of LS174T colon carcinoma c ells in 3 hours. Murine 31.1 had double the response in the range of 3 0% activity. The chimerized version of 31.1 was found to be capable of lysing approximately 90% of colon cancer cells in 3 hrs. Antibody 31. 1 and 33.28 appear to be potentially valuable for diagnostic as well a s therapeutic purposes in patients with colon carcinoma.