Antibody-guided irradiation of malignant ascites in ovarian cancer: a new therapeutic method possessing specificity against cancer cells.

Immunocytology of ascitic fluid of a patient with ovarian cancer demonstrated reactivity with two tumor-associated monoclonal antibodies, AUA1 and HMFG2. AUA1 radiolabeled with 48.6 mCi 131I was given intraperitoneally. There was a reduction in the rate of reaccumulation of ascites. Cytology of recurrent ascites revealed reactivity with antibody HMFG2 but not AUA1. The patient was further treated intraperitoneally with 39.0 mCi 131I-labeled HMFG2. There has been no reaccumulation of ascites. It is concluded that antibody-guided irradiation may be an effective treatment of malignant ascites secondary to ovarian cancer. Furthermore, this case illustrates the specificity of antibody interactions in the mediation of therapeutic effect and the possibility of tumor selection after irradiation with a single monoclonal antibody. If specificity plays a role, all major specificities should be covered by an appropriate panel of radioactively labeled antibodies. It is recommended that for comprehensive therapy of malignant ascites secondary to ovarian cancer, a mixture of antibodies such as HMFG2 and AUA1 should be used.