title: Preparation and comparative evaluation of 99mTc-labeled 2-iminothiolane modified antibodies and CITC-DTPA immunoconjugates of anti-EGF-receptor antibodies.
abstract: The use of antibodies as targeting agents for the delivery of radioisotopes to tumors is a promising concept that has received widespread attention since the advent of monoclonal antibody (mAb) technology. The following studies are described in this article: the 99mTc-randiolabeling of 2-iminothiolane (2-IT) modified antibodies and 6-p-isothiocyanatobenzyl- diethylene-triamine penta-acetic acid (CITC-DTPA) immunoconjugates of anti-EGF-receptor antibodies murine ior egf/r3 and humanized h-R3; the analytical methods for quality control of the radiopharmaceutical such as instant thin layer chromatography-silica gel (ITLC-SG); the biological assessment of the radiolabeled molecule using flow cytometry analysis; in vitro stability studies with cysteine and DTPA challenge and the biodistribution studies in 4NMRI xenografted nude mice with U-87 human glioblastoma multiforme and MDA-MB-468 breast cancer cell lines. Labeling efficency of (96.48 +/- 0.70%) (98.42 +/- 0.38%), (94.8 +/- 1.25%) and (96.41 +/- 0.89%) was achieved for 99mTC-2-IT ior efg/r3, 99mTc-CITC-DTPA- ior egf/r3, 99mTc-CITC-DTPA- h-R3 and 99mTc-DIACIM h-R3, respectively. Radiocolloids were less than 2.0% in all cases. The biological activity measured by flow cytometry analysis using the MDA-MB-468 breast cancer cell line showed an immunoreactivity fraction greater than 85% in all concentrations of each immunoconjugate. Challenge studies demonstrated no evidence of transcomplexation of 99mTc to 1.0 mM DTPA for 2-IT modified antibody ior egf/r3 and CITC-DTPA immunoconjugates and only 8.7%, 4.9% and 5.0% of the 99mTc-radiolabeled was transcomplexed to 1.0 mM cysteine after 1 h incubation at 37 degrees C for 2-IT modified antibody ior egf/r3, CITC-DTPA ior egf/r3 and CITC-DTPA h-R3, respectively. Biodistribution studies with 2-IT modified antibodies and CITC-DTPA immunoconjugates indicated high tumor uptake in both cell lines with both immunoconjugates and no accumulation of the radiolabeled antibodies in normal organs.
authors.affiliation: Institute of Nuclear Medicine and Allied Sciences, Delhi, India.
authors.forename: A K
authors.initials: AK
authors.lastname: Mishra
authors.forename: N
authors.initials: N
authors.lastname: Iznaga-Escobar
authors.forename: R
authors.initials: R
authors.lastname: Figueredo
authors.forename: V K
authors.initials: VK
authors.lastname: Jain
authors.forename: B S
authors.initials: BS
authors.lastname: Dwarakanath
authors.forename: R
authors.initials: R
authors.lastname: Pérez-Rodríguez
authors.forename: R K
authors.initials: RK
authors.lastname: Sharma
authors.forename: T Lazar
authors.initials: TL
authors.lastname: Mathew
mesh_terms: D000230:Adenocarcinoma / Q000276:immunology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry* / Q000378:metabolism / Q000493:pharmacokinetics; D000951:Antigens, Neoplasm / Q000276:immunology; D001943:Breast Neoplasms / Q000737:chemistry / Q000473:pathology; D016543:Central Nervous System Neoplasms / Q000737:chemistry / Q000473:pathology; D003110:Colonic Neoplasms / Q000276:immunology; D003432:Cross-Linking Reagents / Q000737:chemistry / Q000378:metabolism; D004195:Disease Models, Animal; D066246:ErbB Receptors / Q000276:immunology*; D005909:Glioblastoma / Q000737:chemistry / Q000473:pathology; D006801:Humans; D007096:Imidoesters / Q000737:chemistry / Q000378:metabolism; D018796:Immunoconjugates / Q000737:chemistry* / Q000378:metabolism* / Q000493:pharmacokinetics; D007074:Immunoglobulin G / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D015592:Immunoradiometric Assay / Q000379:methods; D017879:Isothiocyanates / Q000737:chemistry* / Q000378:metabolism / Q000493:pharmacokinetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009368:Neoplasm Transplantation / Q000379:methods; D004369:Pentetic Acid / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000378:metabolism / Q000493:pharmacokinetics; D013670:Sodium Pertechnetate Tc 99m / Q000737:chemistry* / Q000378:metabolism / Q000493:pharmacokinetics; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured
chemical_list: C100700:6-(4-isothiocyanatobenzyl)-diethylenetriamine pentaacetic acid; D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D003432:Cross-Linking Reagents; D007096:Imidoesters; D018796:Immunoconjugates; D007074:Immunoglobulin G; D017879:Isothiocyanates; C005905:methyl 4-mercaptobutyrimidate; D004369:Pentetic Acid; D013670:Sodium Pertechnetate Tc 99m; D066246:ErbB Receptors