title: Human breast tumor imaging using 111In labeled monoclonal antibody: athymic mouse model.
abstract: The monoclonal antibody (MoAb) 323/A3, an IgG1, was raised against the human breast tumor cell line MCF-7 and recognized a 43 Kd membrane associated glycoprotein. Histochemical studies with the antibody detected 75% of metastatic lymph nodes, 59% of primary breast tumors, and showed some staining in 20% of benign breast lesions. For radionuclide imaging, the MoAb 323/A3 was labeled with both 125I and 111In, via covalently coupled diethylenetriaminepentaacetic acid (DTPA) by the mixed anhydride method. The antibody activity of the DTPA modified 323/A3 was assessed by an immunoassay using viable and fixed MCF-7 target cells. Male athymic nude mice bearing BT-20 human mammary tumors were injected with dual 125I/111In labeled DTPA 323/A3 via the tail veins. The animals were imaged with a gamma camera equipped with a pinhole collimator at 1-3 h, 1, 2, 3, 4 and 5 days after the tracer administration. On day 5 or 6, the animals were killed, and the biodistribution of the radiotracers was determined for the blood, thyroid, heart, lungs, liver, spleen, kidneys, gastrointestinal tract and tumor. Target to blood ratio at 6 days for the 111In tracer was 24:1 in the group with a mean tumor weight of 0.492 g, and 13:1 in another group with a mean tumor weight of 0.1906 g (day 5). However, the 125I activity showed only 3.6:1 and 5.4:1 target to blood ratios in the corresponding groups. The larger tumors localized less 111In tracer (27.13% +/- 7.57% injected dose/g, Mean +/- SD) than the smaller tumors (52.75% +/- 22.25% ID/g).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Boston 02114.
authors.forename: B A
authors.initials: BA
authors.lastname: Khaw
authors.forename: J S
authors.initials: JS
authors.lastname: Bailes
authors.forename: S L
authors.initials: SL
authors.lastname: Schneider
authors.forename: J
authors.initials: J
authors.lastname: Lancaster
authors.forename: J
authors.initials: J
authors.lastname: Powers
authors.forename: H W
authors.initials: HW
authors.lastname: Strauss
authors.forename: J C
authors.initials: JC
authors.lastname: Lasher
authors.forename: W L
authors.initials: WL
authors.lastname: McGuire
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D006801:Humans; D007205:Indium Radioisotopes; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D011877:Radionuclide Imaging; D014183:Transplantation, Heterologous
chemical_list: D000911:Antibodies, Monoclonal; D007205:Indium Radioisotopes