title: Development of a highly sensitive and specific carboxy-terminal human pancreastatin assay to monitor neuroendocrine tumor behavior.
abstract: OBJECTIVE
  Pancreastatin is a fragment of the chromogranin A (CgA) molecule. Existing pancreastatin assays, which depend on antibodies that cross-react in varying percents with the larger prohormone, may lack sensitivity and specificity to detect small changes in neuroendocrine tumor volume.
  
  
  METHODS
  We developed a highly specific, sensitive pancreastatin assay. The antibody used recognizes the carboxyl terminal of the peptide hormone and was raised against a 17-amino acid porcine pancreastatin fragment with high homology with the carboxy-terminal amino acids 286-301 of the human CgA.
  
  
  RESULTS
  Our assay measures more than 95% of circulating pancreastatin levels; has little or no cross-reactivity with CgA, even at plasma concentrations of 1000 ng/mL; and can detect pancreastatin levels of 17 pg/mL. Interassay reproducibility for the pancreastatin radioimmunoassay was determined from results of 3 quality control pools in 15 consecutive assays. Coefficients of variation for low, medium, and high pancreastatin levels were less than 20%. The sensitivity of serial pancreastatin assays to detect early liver tumor activity was demonstrated in 2 patients with slowly progressive neuroendocrine tumors and in patients undergoing surgical cytoreduction.
  
  
  CONCLUSIONS
  This highly specific, sensitive pancreastatin assay can detect small changes in liver tumor progression and is up to 100-fold more sensitive and specific than CgA assays in the United States.
authors.affiliation: Department of Internal Medicine, University of Iowa Hospitals & Clinics, Iowa City, IA, USA. Thomas-odorisio@uiowa.edu
authors.forename: Thomas M
authors.initials: TM
authors.lastname: O'Dorisio
authors.forename: Siegfried R
authors.initials: SR
authors.lastname: Krutzik
authors.forename: Eugene A
authors.initials: EA
authors.lastname: Woltering
authors.forename: Erika
authors.initials: E
authors.lastname: Lindholm
authors.forename: Saju
authors.initials: S
authors.lastname: Joseph
authors.forename: Abby E
authors.initials: AE
authors.lastname: Gandolfi
authors.forename: Yi-Zarn
authors.initials: YZ
authors.lastname: Wang
authors.forename: J Phillip
authors.initials: JP
authors.lastname: Boudreaux
authors.forename: Aaron I
authors.initials: AI
authors.lastname: Vinik
authors.forename: Vay Liang W
authors.initials: VL
authors.lastname: Go
authors.forename: James R
authors.initials: JR
authors.lastname: Howe
authors.forename: Thor
authors.initials: T
authors.lastname: Halfdanarson
authors.forename: M Sue
authors.initials: MS
authors.lastname: O'Dorisio
authors.forename: Gregg
authors.initials: G
authors.lastname: Mamikunian
mesh_terms: D014408:Biomarkers, Tumor / Q000097:blood*; D053379:Chromogranin A / Q000097:blood; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000097:blood* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000097:blood*; D010187:Pancreatic Hormones / Q000097:blood*; D011863:Radioimmunoassay; D015203:Reproducibility of Results
chemical_list: D014408:Biomarkers, Tumor; D053379:Chromogranin A; D010187:Pancreatic Hormones; C050836:pancreastatin