TUMOR UPTAKE OF INTRAVENOUSLY ADMINISTERED RADIOLABELED ANTIBODIES INOVARIAN-CARCINOMA PATIENTS IN RELATION TO ANTIGEN EXPRESSION AND OTHER TUMOR CHARACTERISTICS

To study factors that possibly influence the heterogeneous tumor uptak e of radiolabeled antibodies, tissues from 34 ovarian-carcinoma patien ts were obtained 2 to 8 days after i.v. injection with radiolabeled mu rine OV-TL 3 or chimeric MOv 18 (cMOv 18). The tumor uptake and the ra tio of tumor to normal tissue (T/NT) were studied in relation to the h istopathological classification, prior treatment, site of tumor, time interval, antigen expression, volume percentage of (malignant) epithel ium in the tumor tissue, and the size of the tumor. The results of imm unoscintigraphy were also included. In addition, autoradiography using storage phosphor technology was performed on tissue sections from pat ients injected with iodine-labeled cMOv 18. Tumor uptake varied largel y, not only between patients, but also between tumor deposits within t he same patient. Uptake of OV-TL 3 F(ab')(2) was higher than of cMOv 1 8 F(ab')(2), but the T/NT ratios were similar. The antibody uptake was positively correlated with the pattern of antigen expression and inve rsely correlated with the time interval between injection and surgery. No correlation was observed with any of the other factors studied. Th e visibility with immunoscintigraphy was related to the size of the de tected lesion, but not to the other factors studied. Autoradiography s howed that antibodies preferentially localized in areas with cancer ce lls, which were immunohistochemically positive for MOv 18. In areas wi th weak antigen expression, autoradiography revealed less activity. Th e antigen expression by the tumor is an important factor for estimatio n of the tumor uptake of radiolabeled antibodies. (C) 1995 Wiley-Liss, Inc.