Perfusion of tumor-bearing kidneys as a model for scintigraphic screening of monoclonal antibodies.

Tumor-bearing human kidneys were used in an ex vivo perfusion model to screen monoclonal antibodies, recognizing renal cell carcinoma-associated antigens for diagnostic potential in vivo. Perfusion of tumor-bearing kidneys with 99mTc-labeled G250 and RC38 antibody resulted in visualization of the tumor, whereas perfusion with two other monoclonal antibodies, RC2 and RC4, did not lead to tumor visualization. Uptake of radiolabel in normal kidney tissue was low for G250 and RC38 antibody. Tumor-to-kidney tissue ratios after perfusion with G250 and RC38 antibody were 2.7 and 2.2, respectively. After rinsing for 3 hr with unlabeled perfusion fluid the tumor-to-kidney tissue ratios increased to 8.6 for G250 antibody and to 2.7 for RC38 antibody. We conclude that perfusion of tumor-bearing human kidneys with radiolabeled monoclonal antibodies is a relatively simple way to evaluate renal cell carcinoma associated monoclonal antibodies as diagnostic agents in vivo.