Primary hepatocellular carcinoma localised by a radiolabelled monoclonal antibody

A rat monoclonal antibody, YPC2/38.8, was selected from a panel of antibodies derived by immunising rats with fresh human colorectal carcinoma. It was found to bind to a 30 000 dalton protein present on the cell surface of normal colon and liver. This protein was increased 10-fold on primary hepatocellular carcinoma (PHC) cells. After labelling with 131I, YPC2/38.8 was shown to localise human PHCs grown as xenografts in immunosuppressed mice. Sixteen patients with PHC were given 1 mg of purified antibody labelled with 1 mCi of 131I by slow intravenous injection. In 8 out of 9 patients with PHC arising in non-cirrhotic livers, good tumour images were obtained on gamma camera or rectilinear scans, but in 7 patients who had developed PHC on the background of established hepatic cirrhosis, no tumour images were seen. Subsequent studies revealed that the 30K antigen recognised by this antibody was present in increased quantity on PHC cells and the regenerating liver cells in cirrhosis. We conclude that YPC2/38.8 may have potential for diagnostic localisation and possibly thence for the selective targeting of drugs or toxins in patients with PHC arising in a liver unaffected by significant parenchymal disease.