EXPRESSION OF POTENTIAL TARGET ANTIGENS FOR IMMUNOTHERAPY ON PRIMARY AND METASTATIC PROSTATE CANCERS

Defining the expression of tumor-associated antigens on primary and me tastatic prostate cancer is the crucial first step in selecting approp riate targets for immune attack. In this study, the distribution of th e tumor-associated antigens GM2, Tn, sTn, Thompson-Friedenreich antige n (TF), Globe H, Le(y), MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC7, c arcinoembryonic antigen, beta chain of human chorionic gonadotropin (h CG beta), HER2/neu, PSMA, and KSA on primary and metastatic prostate c ancer and 16 types of normal tissues was compared by immunohistochemis try, using a panel of well-characterized monoclonal antibodies. Our re sults show that GM2, KSA, and MUC2 were strongly expressed on 8 or 9 o f 9 metastatic prostate cancer biopsy specimens and, with PSMA, hCG be ta, TF, Tn, and sTn, on 8 or more of II primary prostate cancer specim ens. Tn, MUC1, and PSMA were expressed on 4-6 of 9 metastatic specimen s. The remaining antigens were expressed on no more than three of nine metastatic specimens. Normal tissues were also tested with all antibo dies. With regard to the eight antigens most widely expressed on prost ate cancers, PSMA was not expressed significantly on any of the normal tissues except prostate epithelium. Tn, sTn, hCG beta, and MUC2 were detected on up to 3 of 10 types of normal epithelia. GM2, TF, MUC1, an d KSA were more broadly distributed on normal epithelia, all primarily at the secretory borders. STn, KSA, and hCG beta were also detected i n the testis, and GM2 was expressed on gray matter of brain. From the 30 antigens that we have screened, this study provides the basis for s electing GM2, TF, Tn, sTn, hCG beta, MUC1, MUC2, KSA, and PSMA as targ et antigens for specific immunotherapy of prostate cancer.