[Clinical application of cancer-associated carbohydrate antigens in the diagnosis and therapy of human cancers]

Abstract

Cell surface carbohydrates are important cancer-associated antigens. The carbohydrate antigens which have been proved to be useful for the serum diagnosis of human cancers are classified from their biochemical primary structure into three categories; the type 1 chain antigens, type 2 chain antigens, and core structure-associated antigens. The SPan-1 antigen, the newly-introduced tumor marker for human pancreas cancers, seems to be a type 1 chain antigen, judging from its distribution pattern among human cancers and its good correlation with other type 1 chain antigens. Another newly-introduced tumor marker, the CA54/61 antigen, which is specific for ovarian cancers, seems to belong to the family of the core-structure-associated antigens, since both antibodies (MA54 and MA61) used for the detection of the CA54/61 antigen are shown to recognize the antigen molecule which is closely related to sialyl Tn antigen, the well-known carbohydrate core structure of mucins. There are two approaches for the therapy of human cancers employing carbohydrate antigens as target molecules. One is the direct application of the specific monoclonal antibodies (alone, or in the drug-conjugated forms) in cancer patients. In this case, special attention is paid to the use of murine antibodies in human patients. The other approach is to induce specifically an effective immune response against the cancer-associated carbohydrate antigens. For this approach, further methodological development is necessary to determine how to obtain an effective immune response to carbohydrate antigens, since they have long been known as very poor immunogens which are T-independent.