Prognostic utility of a glycoprotein tumor-associated antigen (TA90) specific immune complex assay in patients with cancer

This review summarizes the development and applicability of an assay to detect an immune complex (IC) of a 90kD glycoprotein tumor-associated antigen (TA90). The antigen is immunogenic in the cancer host and expressed by a variety of solid tumors. In circulation, it induces formation of endogenous antigen-antibody complexes. The presence of TA90-IC has been detected in significantly greater proportions of serum samples from cancer patients compared to normal controls. The postoperative presence of TA90-IC in circulation strongly correlated with subsequent development of clinically detectable recurrence within an average interval of 3 to 19 months. The TA90-IC status after surgery but before initiation of adjuvant therapy consistently correlated with disease-free survival and overall survival. Because of its ability to accurately detect subclinical metastasis and predict survival 1 to 3 months after surgical resection of early-stage cancer, TA90-IC represents a novel and feasible prognostic marker to select candidates for adjuvant therapies and to stratify patients in clinical trials. Expression of TA90 by melanoma, colon cancer, lung cancer, breast cancer and other solid neoplasms makes TA90-IC an ideal marker in the management of early-stage cancer. Its specificity can be significantly enhanced if positive samples are subsequently analyzed by a panel of tumor markers characteristic for a particular type of cancer, such as CA15-3 for breast cancer and carcinoembryonic antigen (CEA) for colon cancer. TA90-IC could be used in conjunction with these site-specific markers as part of a cancer screening program to identify high-risk individuals for closer surveillance.