Clinical application of a new monoclonal antibody (19B7) against PIVKA-II in the diagnosis of hepatocellular carcinoma and pancreatobiliary malignancies.

Abstract

A new monoclonal antibody (19B7) against prothrombin induced by vitamin K absence or antagonist-II (PIVKA-II) was clinically applied in patients diagnosed with hepatocellular carcinoma and pancreatobiliary malignancies, and the results were compared with those obtained using the conventional monoclonal antibody (MU-3) against PIVKA-II. The assays were the standard E-1023 using MU-3, a high sensitivity kit using MU-3 and a highly sensitive avidin-biotin complex method, and a new monoclonal antibody (19B7) kit. The rate of PIVKA-II positivity in patients with hepatocellular carcinoma (n = 182) was 44% with E-1023, 55.5% with the high sensitivity kit, and 58.2% with the new monoclonal antibody kit. Small liver cancers <2 cm in diameter (n = 45) had a positivity rate of 15.6% with E-1023, 26.7% with the high sensitivity kit, and 31.1% with the new monoclonal antibody kit. The incidence of PIVKA-II positivity in patients with pancreatobiliary carcinoma (n = 91) was 29.7% with the high sensitivity kit and 52.7% with the new monoclonal antibody kit. The PIVKA-II ratio (plasma concentration with the high sensitivity kit/plasma concentration with the new monoclonal antibody kit) was calculated as > 1.0 in 89 of the 113 (78.8%) patients with hepatocellular carcinoma with the new monoclonal antibody kit assay level above 0.002 arbitrary units/ml, compared with <1.0 in almost all patients with pancreatobiliary malignancies. MU-3 has much greater affinity for PIVKA-II in hepatocellular carcinoma than does 19B7, whereas 19B7 has much greater affinity for PIVKA-II in pancreatobiliary malignancies than does MU-3. The new monoclonal antibody, 19B7, is useful for diagnosing hepatocellular carcinoma and can also distinguish patients with hepatocellular carcinoma from those with other pancreatobiliary malignancies when combined with a PIVKA-II assay using the conventional monoclonal antibody, MU-3.