[Significance and application of anti-malignant hepatoma MAb HAb18 in radioimmunal diagnosis of human hepatocellular carcinoma].

In this study, 125I or 131I labelled intact IgG and its F(ab')2 fragments of an antihuman hepatoma monoclonal antibody, HAb18, was used for in vivo radioimmunoimaging of malignant hepatomas. Clear imaging of the tumor was obtained in 168 hours for intact IgG or in 72 hours for F(ab')2 fragments after iv injection or via selective catheterization of the arteriae hepatica communis. In addition, 99mTc-PHY (500 microCi) was simultaneously injected for static scanning of the liver, with which the tumor appeared as defects. All the 20 patients in this study were operated and the lesions were pathologically examined to verify the imaging results. The tumor: liver isotopic ratios were 2.15 +/- 0.15 and 2.63 +/- 0.21 for intact IgG and F(ab')2 fragments, respectively. In other vital organs, such as heart, brain, spleen, lungs and kidneys, as well as non-hepatoma neoplasms, including 3 cases of liver cavernous hemangioma and 2 cases of gastric cancer metastasized to the liver, no radioisotopic concentration was observed. Both the labelled IgG and F(ab')2 fragments had the same targeting potential, but a better contrast was obtained with F(ab')2 fragments. Furthermore, its clearance rate was faster than intact IgG. The smallest tumor diagnosed with this antibody was 0.5 cm in diameter and the positive rate for imaging primary hepatoma was 86.7% (13/15). The results obtained in this study promisingly indicate that HAb18 antibody may become the first choice for the early radioimmunodetection of human hepatoma.