Human monoclonal antibody developed against ovarian cancer cell surface antigen

Background. Murine monoclonal antibodies (MoAb) potentially can be used in the radioimmunodetection and radioimmunotherapy of cancer. However, the administration of these radiopharmaceuticals to humans often leads to induction of human anti‐murine antibodies (HAMA). HAMA has many disadvantages, which could decrease efficacy of the murine MoAb. The purpose of this work was to produce human monoclonal antibody against a human ovarian cancer cell surface antigen (OCCSA), which was not present in normal ovarian cells. This 200‐kilodalton OCCSA also was used in the present study for characterizing the human monoclonal antibody. Methods. Human monoclonal antibodies were produced in vitro by fusion of mutant myeloma cells, selected from GM1500, with human lymphoid cells immunized in vitro with purified OCCSA. The human monoclonal antibody was characterized using the following techniques: sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE), native‐PAGE, Western blotting followed by protein‐A gold staining, immunodiffusion assays, and fluorescent antibody assays. Results. Human monoclonal antibody, TC5 (immunoglobulin G1), was produced and purified. It was found to be specific for ovarian cancer, while also reacting with an early stage breast cancer. TC5 did not react with any normal (i.e., nonneoplastic) cells of the ovary, uterus, cervix, endocervix, or fallopian tube, nor did it react with normal lung, heart, pancreas, liver, or breast tissue. Conclusion. Human‐human hybridomas produced human monoclonal antibody against OCCSA. The human monoclonal antibody, TC5, was specific for ovarian and breast cancer. TC5 did not react with any normal tissue tested. Future work will focus on the in vivo characterization of the human monoclonal antibody, after labeling with radionuclides. Cancer 1994; 73:1098–104.