Identification of colon tumour-associated antigens by phage antibody selections on primary colorectal carcinoma

Immunotargeting of solid tumours using antibodies has become a valuable too l for the detection of cancer metastases and the treatment of minimal resid ual disease. However, only few tumour antigens useful for targeting have be en described to date. To identify cell-surface targets on colorectal carcin oma (CRC), we selected a large, human phage antibody repertoire on freshly isolated colon tumour cells. Two antibodies were identified that reacted wi th epithelial cell-restricted cell-surface antigens, whereas one clone pref erentially reacted with stromal cells. These antigens are tumour-associated antigens, as shown by their uniform expression in tumours of different pat ients and of different differentiation stages and by their limited expressi on on normal tissues. The pattern of reactivity in immunohistochemistry (IH C) and enzyme-linked immunosorbent assay (ELISA) suggests that: these antig ens are different from previously identified tumour-associated antigens (e. g. Ep-CAM or c-ERB-2). This phage antibody-based method may lead to the clo ning of novel tumour antigens that are useful for the immunotargeting of so lid rumours. (C) 2001 Elsevier Science Ltd. All rights reserved.