Biodistribution of 131I-labelled monoclonal antibodies in human colon tumours by an ex vivo perfusion model.

We describe a model for the evaluation of anti-tumour antibody specificity, using a human carcinoma-bearing colon segment. After resection of the human colon tumour, the supplying artery was cannulated and perfused with fresh frozen plasma and heparin. Continuous control of pressure, flow, temperature, pH and various metabolic parameters were performed after administration of 131I-labelled anti-CEA antibody. Highly differentiated adenocarcinomas of the colon showed a much higher antibody uptake than undifferentiated tumours. Between 3 and 7% of the injected antibody was found in the tumour tissue. Autoradiography showed non-homogeneous binding in the tumour tissue. The non-specific antibody perfusion showed no tumour binding. We conclude that the ex vivo perfusion of resected colon carcinomas can be used to measure the kinetics of binding and clearance of MAbs in tumour tissue by direct scintigraphy. The cellular biodistribution of the antibody can be documented by means of autoradiography.