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 2780(AD). 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.