New application of human tumor clonogenic assay to in vitro evaluation of tumor-targeting efficiency of immunoconjugates.
This report proposes an efficient in vitro method for the evaluation of drug targeting with monoclonal antibody as a carrier to tumor cells. Monoclonal antibody (35G; IgG2a) selectively binding to alpha-fetoprotein (AFP) from human hepatoma cells (HuH-7) was conjugated with an anticancer drug, vindesine (VDS). Human tumor clonogenic assay (HTCA) with some modifications was applied to estimate the targeting efficiency of a conjugate (VDS-35G) for the first time. In this assay, VDS-35G was cytotoxically active against HuH-7 cells at a lower concentration (0.5 ng/ml) and for a shorter contact time than VDS (50 ng/ml), while 35G and VDS-normal mouse immunoglobulin conjugate (VDS-n-IgG) were not active against the cells. Both VDS-35G and VDS-n-IgG were inactive against HuH-13 cells established from a human hepatocellular carcinoma producing no AFP. In the conventional monolayer culture assay (MCA), VDS-35G showed little effect on HuH-7 cells at the concentration effective in HTCA. The cytotoxic activity of VDS in MCA was similar to that in HTCA but the cytotoxic activity of VDS-35G in MCA was considerably different from that in HTCA. This discrepancy could be explained by the hypothesis that VDS-35G was directed at stem cells of the HuH-7 cell population sensitively and selectively. HTCA was shown to be a useful in vitro evaluation method for drug targeting.
Nagata
S
S
Shionogi Research Laboratories, Shionogi & Co., Ltd., Osaka, Japan.
Masuda
K
K
Nogusa
H
H
Hirano
K
K
Takagishi
Y
Y
D000818:Animals; D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D002999:Clone Cells / Q000187:drug effects*; D004337:Drug Carriers; D006801:Humans; D008114:Liver Neoplasms, Experimental / Q000188:drug therapy / Q000276:immunology; D014410:Tumor Stem Cell Assay
D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D004337:Drug Carriers