title: Preclinical evaluation of (177)lu-nimotuzumab: a potential tool for radioimmunotherapy of epidermal growth factor receptor-overexpressing tumors.
abstract: BACKGROUND
  The humanized monoclonal antibody Nimotuzumab (h-R3) has demonstrated an exceptional and better clinical profile than other monoclonal antibodies for immunotherapy of epidermal growth factor receptor-overexpressing tumors. This work deals with the preparation and radiolabeling optimization of (177)Lu-Nimotuzumab and their preclinical evaluation.
  
  
  METHODS
  Nimotuzumab was conjugated with S-2-(4-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane tetraacetic acid (p-SCN-Bn-DOTA), testing different molar ratios. The immunoconjugates were characterized. The radiolabeling with (177)Lu was optimized. Radioimmunoconjugates stability was tested in 2-[bis[2-[bis(carboxymethyl)amino]ethyl]amino]acetic acid (DTPA) excess and human serum. In vitro studies were performed in tumor model cell lines. Receptor-specific binding was tested by competitive inhibition. (177)Lu-Nimotuzumab in vivo studies were conducted in healthy and xenograft animals.
  
  
  RESULTS
  Nimotuzumab conjugates were obtained with high purity. Radiolabeling yield and specific activities ranged from 63.6% to 94.5% and from 748 to 1142 MBq/mg, respectively. The stability in DTPA excess and human serum was 95.9% and 93.2% after 10 days, respectively. The radioimmunoconjugate showed specific receptor binding in tumor cell lines. Biodistribution in healthy animals showed the typical behavior of the immunoconjugates based on monoclonal antibodies. The study in xenografts mice demonstrated uptake of (177)Lu-Nimotuzumab in the tumor and reticuloendothelial organs.
  
  
  CONCLUSIONS
  (177)Lu-Nimotuzumab was obtained with high purity and specific activities under optimal conditions without significant loss in immunoreactivity and might be a potential radioimmunoconjugate for radioimmunotherapy of tumors with epidermal growth factor receptor overexpression.
authors.affiliation: Radiopharmaceutical Department, Nuclear Physics Institute of the Academy of Sciences, Husinec-Rez, Czech Republic. beckford@ujf.cas.cz
authors.forename: Denis Rolando Beckford
authors.initials: DR
authors.lastname: Vera
authors.forename: Sebastian
authors.initials: S
authors.lastname: Eigner
authors.forename: Milos
authors.initials: M
authors.lastname: Beran
authors.forename: Katerina Eigner
authors.initials: KE
authors.lastname: Henke
authors.forename: Alice
authors.initials: A
authors.lastname: Laznickova
authors.forename: Milan
authors.initials: M
authors.lastname: Laznicek
authors.forename: Frantisek
authors.initials: F
authors.lastname: Melichar
authors.forename: Marco
authors.initials: M
authors.lastname: Chinol
mesh_terms: D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use*; D045744:Cell Line, Tumor; D002614:Chelating Agents / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D066246:ErbB Receptors / Q000096:biosynthesis*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006571:Heterocyclic Compounds / Q000494:pharmacology; D006801:Humans; D018796:Immunoconjugates / Q000627:therapeutic use*; D017879:Isothiocyanates / Q000494:pharmacology; D008187:Lutetium / Q000627:therapeutic use*; D051379:Mice; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000628:therapy*; D016499:Radioimmunotherapy / Q000379:methods*; D011868:Radioisotopes / Q000627:therapeutic use*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
chemical_list: C087160:2-(4-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane tetraacetic acid; D061067:Antibodies, Monoclonal, Humanized; D002614:Chelating Agents; D006571:Heterocyclic Compounds; D018796:Immunoconjugates; D017879:Isothiocyanates; D011868:Radioisotopes; D008187:Lutetium; C501466:nimotuzumab; D066246:ErbB Receptors