The treatment of intraperitoneal malignant disease with monoclonal antibody guided 131I radiotherapy.

Seven patients with small volume ovarian carcinoma, remaining after conventional therapy with surgery and a platinum containing chemotherapy regimen, were treated with intraperitoneal monoclonal antibody guided radiotherapy. 100 mCi131I conjugated to 10 mg of monoclonal antibody were injected i.p. in 2,000 ml peritoneal dialysis fluid. Patients were evaluated 3 months later; 3 had clinical progressive disease while third look laparotomy demonstrated progressive disease in 3 of the remaining 4 patients. The seventh patient did not have a third look laparotomy and is currently inevaluable for response. Five patients with recurrent malignant ascites not controlled by diuretics or repeated paracentesis were similarly treated with 75-170 mCi131I conjugated to 10 mg monoclonal antibody. In three patients the ascites was controlled for a mean of 4 months. One patient died too early to assess the control of his ascites but tumour cells disappeared from the ascitic fluid after therapy. In the patient whose ascites were not controlled, a subpopulation of antigen-negative tumour cells was demonstrated. This study was unable to demonstrate a therapeutic benefit for i.p. injected monoclonal antibody guided radiotherapy for solid intraperitoneal tumour but suggests that it may be capable of controlling the accumulation of antigen positive malignant ascites.