单克隆抗体与博来霉素A6偶联物对肝癌的实验研究

用Dextran T40为中介体的方法偶联抗人肝癌单抗Hlll和博来霉素A6,体外实验显示Hlll与A6偶联物对人肝癌细胞抑制90%克隆生成浓度(IC₉₀)为0.17μmol/L:游离A6以及无关抗体与A6偶联物M3-A6分别为17/μmol/L和7μmol/L;同时加入Hlll单抗明显降低Hill-A6偶联物的细胞毒性;体内实验证明:Hlll-A6偶联物对裸鼠移植的人肝癌抑制率达78%,等剂量A6,M3-A6偶联物和Hlll与A6混合物的抑制率均约为30%。结果表明单抗Hlll与A6偶联物对肝癌的抑制作用明显比游离A6强。

EXPERIMENTAL STUDIES ON THE ANTITUMOR ACTIVITY OF MONOCLONAL ANTIBODY-BLEOMYCIN A6 CONJUGATE AGAINST HUMAN LIVER CANCER.

Bleomycin A6 (A6), a single component of bleomycin complex, is highly active against human liver cancer cells in vitro and xenografts in nude mice. A6 was conjugated to monoclonal antibody H111 directed against human hepatoma BEL - 7402 cells, using Dextran T40 as an intermediate. The conjugate consisted of a coupling molar ratio of 1:264 for H111 and A6, and retained 6.3% of A6 activity. As determined by clonogenic assay with hepatoma BEL - 7402 cells exposed to the agents for 1 h, the IC90 values for H111 - A6 conjugate, free A6 and M3 - A6 conjugate (an irrelevant conjugate) were 0.17 mu mol/L, 17 mu mol/L and 7 mu mol/L respectively. The cytotoxicity of Hill - A6 conjugate to target cells was markedly blocked by unconjugated H111 but not by irrelevant monoclonal antibody M3. The H111 - A6 conjugate exhibited 78% inhibition on the growth of hepatoma BEL - 7402 xenografts in nude mice, whereas the equivalent doses of free A6, M3 - A6 conjugate and H111 plus A6 mixture showed approximately 30% inhibition. Histopathological examination showed no toxic changes in the liver, lung, kidney and bone marrow in the H111 - A6 conjugate--treated animals. These results suggest that the conjugate of monoclonal antibody and bleomycin A6 exhibits specific cytotoxicity to target liver cancer cells and the conjugate is highly effective against liver cancer xenografts in nude mice with more marked tumor inhibition than free A6 at comparable dose levels.