I-131-labelled chimeric monoclonal antibody MOv18 in ovarian cancer patients: a pilot study

MOv18 binds an epitope on membrane folate receptors, highly expressed on ov arian carcinoma cells. Previous extensive clinical studies with c-MOv18 dem onstrated preferential localization in tumour tissue of ovarian cancer pati ents. To study the safety and logistics of a treatment with I-131-labelled c-MOv1 8, 2 patients were injected intravenously (i.v.) with 740 MBq I-131-c-MOv18 IgG. Toxicity was evaluated according to WHO toxicity scales. Blood sampli ng was performed for 12 weeks post injection. Imaging was performed within Ih and frequently thereafter. Dose rates were obtained twice a day at vario us distances from patients with a portable dose rate measure. According to Dutch governmental regulations, the dose rate at 1 m from the patient shoul d be below 20 mu Sv/h (400 MBq) upon discharge. Quantitative activity analy sis of several organs was performed with the region of interest technique. Absorbed doses were calculated using MIRDOSE 3. For red marrow dose calcula tions, an activity ratio between red marrow and blood of 0.3 was used. Admi nistration of I-131-c-MOv18 was uneventful. Mean isolation time was 4 1/2 d . No significant changes in haematological, biochemical, or urine profile w ere observed for more than 12 weeks. Blood kinetics were as reported earlie r. Dosimetric analyses showed a mean absorbed dose of 39, 92, 115, and 51 c Gy for whole body, liver, spleen, and red marrow, respectively. In conclusion, i.v. administration of I-131-c-MOv18 IgG was safe. No toxici ty or psychological side effects were observed. The efficiency of dose rate measurements with a portable device adequately predicted the day of discha rge from the hospital.