Inhibition of Multidrug‐resistant Human Tumor Growth in Athymic Mice by Anti‐P‐glycoprotein Monoclonal Antibodies

In an effort to devise an effective treatment for human drug-resistant cancers, we have developed monoclonal antibodies, MRK16 and 17, reactive to the multidrug transporter protein, P-glycoprotein. The monoclonal antibodies given intravenously effectively prevented tumor development in athymic mice inoculated subcutaneously with drug-resistant human ovarian cancer cells 2780AD. Treatment with MRK16 induced rapid regression of established subcutaneous tumors and apparent cures of some animals. Complement-dependent cytotoxicity (MRK16) and antibody-dependent cell-mediated cytolysis (MRK16 and 17) were observed with these antibodies. These monoclonal antibodies may have potential as treatment tools against multidrug resistant human tumors possessing the P-glycoprotein.