title: Radiolabeled chimeric anti-CEA monoclonal antibody compared with the original mouse monoclonal antibody for surgically treated colorectal carcinoma.
abstract: Biodistribution and tumor uptake of a chimeric human-mouse monoclonal antibody (MAb) and the original mouse MAb have been comparatively studied.
  
  
  METHODS
  Eighteen patients with suspected colorectal cancer scheduled for surgery underwent immunoscintigraphy with 123I-labeled chimeric anti-CEA MAb. Iodine-125 and 131I trace-labeled chimeric and original mouse MAb were simultaneously injected for biodistribution studies.
  
  
  RESULTS
  Similar serum kinetics and a low immunogenicity were observed for both antibodies. Mean binding capacity to CEA measured in PBS after radiolabeling was identical for both MAbs and it was slightly decreased when measured in serum 1-4 hr after injection. Radiochromatograms of patients sera showed immune complex formation related to the amount of circulating CEA. Postoperative ex vivo radioactivity counting in tissue samples revealed similar antibody distributions with notably similar antibody uptakes in tumors. High tumor uptakes (between 0.02 to 0.06% injected dose per g) were observed in 3 of 13 patients operated for primary or metastatic colorectal cancer.
  
  
  CONCLUSIONS
  In this dual-label technique, the radioiodinated anti-CEA IgG4 chimeric MAb and the original mouse IgG1 MAb were shown to have very similar behavior in colorectal cancer patients.
authors.affiliation: Department of Surgery, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Buchegger
authors.forename: J P
authors.initials: JP
authors.lastname: Mach
authors.forename: A
authors.initials: A
authors.lastname: Pèlegrin
authors.forename: M
authors.initials: M
authors.lastname: Gillet
authors.forename: C A
authors.initials: CA
authors.lastname: Vogel
authors.forename: T
authors.initials: T
authors.lastname: Buclin
authors.forename: J E
authors.initials: JE
authors.lastname: Ryser
authors.forename: B
authors.initials: B
authors.lastname: Delaloye
authors.forename: A B
authors.initials: AB
authors.lastname: Delaloye
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000911:Antibodies, Monoclonal / Q000493:pharmacokinetics; D002272:Carcinoembryonic Antigen / Q000276:immunology*; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008875:Middle Aged; D016719:Radioimmunodetection; D011993:Recombinant Fusion Proteins / Q000493:pharmacokinetics
chemical_list: D000911:Antibodies, Monoclonal; D002272:Carcinoembryonic Antigen; D011993:Recombinant Fusion Proteins