title: Comparison of iodine-123-vasoactive intestinal peptide receptor scintigraphy and indium-111-CYT-103 immunoscintigraphy.
abstract: Recently, we have shown that the expression of receptors for vasoactive intestinal peptide (VIP) on intestinal adenocarcinomas can be used for in vivo targeting of primary or metastatic tumor sites using 123I-labeled VIP. Several other receptors and antigens including the TAG-72 protein have also been implemented for in vivo localization purposes. In this study, we have compared the in vitro and in vivo binding of 123I-VIP and of the 111In-labeled monoclonal antibody (MAb) directed against TAG-72 (OncoScint; 111In-CR-103) in patients with intestinal adenocarcinomas in a single-blinded, prospectively randomized trial.
  
  
  METHODS
  Twenty patients were administered either 123I-VIP (150-200 MBq; 1 microgram) or 111In-CYT-103 (150 MBq; 1 mg) for one imaging study. After interim analysis demonstrated superior imaging with 123I-VIP, the next 10 patients (accounting for a total of 50 patients) enrolled in this trial underwent both studies in random order to allow for a direct comparison.
  
  
  RESULTS
  In total, 123I-VIP scans were true-positive in 28 of 30 patients (93%) versus 17 of 30 patients administered 111In-CYT-103 (56%). In the subgroup of 10 patients enrolled in the second part of the study, primary intestinal adenocarcinomas were imaged in five of five patients with 123I-VIP and in only two of these patients with 111In-CYT-103. Liver metastases were visualized in five of six patients by 123I-VIP receptor scanning and in four of these patients with 111In-CYT-103. The in vitro results indicated significant binding of 123I-VIP to primary colorectal tumors as well as to HT29 and COLO320 adenocarcinoma cells. In vitro, adenocarcinoma cells also expressed abundant numbers of the TAG-72 antigen.
  
  
  CONCLUSIONS
  Intestinal adenocarcinomas co-express VIP receptors and the IAG-72 antigen. Despite significant in vitro binding of both agents, however, the VIP receptor scan is more sensitive in localizing intestinal adenocarcinomas and metastatic spread.
authors.affiliation: Department of Nuclear Medicine, University of Vienna, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Raderer
authors.forename: A
authors.initials: A
authors.lastname: Becherer
authors.forename: A
authors.initials: A
authors.lastname: Kurtaran
authors.forename: P
authors.initials: P
authors.lastname: Angelberger
authors.forename: S
authors.initials: S
authors.lastname: Li
authors.forename: M
authors.initials: M
authors.lastname: Leimer
authors.forename: G
authors.initials: G
authors.lastname: Weinlaender
authors.forename: G
authors.initials: G
authors.lastname: Kornek
authors.forename: K
authors.initials: K
authors.lastname: Kletter
authors.forename: W
authors.initials: W
authors.lastname: Scheithauer
authors.forename: I
authors.initials: I
authors.lastname: Virgolini
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging* / Q000556:secondary; D000911:Antibodies, Monoclonal; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000000981:diagnostic imaging*; D006801:Humans; D007205:Indium Radioisotopes; D007457:Iodine Radioisotopes; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary; D008297:Male; D008875:Middle Aged; D009842:Oligopeptides; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging*; D004369:Pentetic Acid / Q000031:analogs & derivatives*; D011446:Prospective Studies; D016719:Radioimmunodetection; D018005:Receptors, Vasoactive Intestinal Peptide / Q000032:analysis*; D016037:Single-Blind Method; D014407:Tumor Cells, Cultured; D014660:Vasoactive Intestinal Peptide
chemical_list: D000911:Antibodies, Monoclonal; C063430:Indium 111In-satumomab pendetide; D007205:Indium Radioisotopes; D007457:Iodine Radioisotopes; D009842:Oligopeptides; D018005:Receptors, Vasoactive Intestinal Peptide; D014660:Vasoactive Intestinal Peptide; D004369:Pentetic Acid