title: Validation of four candidate pancreatic cancer serological biomarkers that improve the performance of CA19.9.
abstract: BACKGROUND
  The identification of new serum biomarkers with high sensitivity and specificity is an important priority in pancreatic cancer research. Through an extensive proteomics analysis of pancreatic cancer cell lines and pancreatic juice, we previously generated a list of candidate pancreatic cancer biomarkers. The present study details further validation of four of our previously identified candidates: regenerating islet-derived 1 beta (REG1B), syncollin (SYCN), anterior gradient homolog 2 protein (AGR2), and lysyl oxidase-like 2 (LOXL2).
  
  
  METHODS
  The candidate biomarkers were validated using enzyme-linked immunosorbent assays in two sample sets of serum/plasma comprising a total of 432 samples (Sample Set A: pancreatic ductal adenocarcinoma (PDAC, n = 100), healthy (n = 92); Sample Set B: PDAC (n = 82), benign (n = 41), disease-free (n = 47), other cancers (n = 70)). Biomarker performance in distinguishing PDAC from each control group was assessed individually in the two sample sets. Subsequently, multiparametric modeling was applied to assess the ability of all possible two and three marker panels in distinguishing PDAC from disease-free controls. The models were generated using sample set B, and then validated in Sample Set A.
  
  
  RESULTS
  Individually, all markers were significantly elevated in PDAC compared to healthy controls in at least one sample set (p ≤ 0.01). SYCN, REG1B and AGR2 were also significantly elevated in PDAC compared to benign controls (p ≤ 0.01), and AGR2 was significantly elevated in PDAC compared to other cancers (p < 0.01). CA19.9 was also assessed. Individually, CA19.9 showed the greatest area under the curve (AUC) in receiver operating characteristic (ROC) analysis when compared to the tested candidates; however when analyzed in combination, three panels (CA19.9 + REG1B (AUC of 0.88), CA19.9 + SYCN + REG1B (AUC of 0.87) and CA19.9 + AGR2 + REG1B (AUC of 0.87)) showed an AUC that was significantly greater (p < 0.05) than that of CA19.9 alone (AUC of 0.82). In a comparison of early-stage (Stage I-II) PDAC to disease free controls, the combination of SYCN + REG1B + CA19.9 showed the greatest AUC in both sample sets, (AUC of 0.87 and 0.92 in Sets A and B, respectively).
  
  
  CONCLUSIONS
  Additional serum biomarkers, particularly SYCN and REG1B, when combined with CA19.9, show promise as improved diagnostic indicators of pancreatic cancer, which therefore warrants further validation.
authors.affiliation: Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada. ediamandis@mtsinai.on.ca.
authors.forename: Shalini
authors.initials: S
authors.lastname: Makawita
authors.forename: Apostolos
authors.initials: A
authors.lastname: Dimitromanolakis
authors.forename: Antoninus
authors.initials: A
authors.lastname: Soosaipillai
authors.forename: Ireena
authors.initials: I
authors.lastname: Soleas
authors.forename: Alison
authors.initials: A
authors.lastname: Chan
authors.forename: Steven
authors.initials: S
authors.lastname: Gallinger
authors.forename: Randy S
authors.initials: RS
authors.lastname: Haun
authors.forename: Ivan M
authors.initials: IM
authors.lastname: Blasutig
authors.forename: Eleftherios P
authors.initials: EP
authors.lastname: Diamandis
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000594:Amino Acid Oxidoreductases / Q000097:blood; D014408:Biomarkers, Tumor / Q000097:blood*; D018395:CA-19-9 Antigen / Q000097:blood*; D002352:Carrier Proteins / Q000097:blood*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D051847:Lithostathine / Q000097:blood*; D008297:Male; D008565:Membrane Proteins / Q000097:blood*; D008875:Middle Aged; D009088:Mucoproteins; D009367:Neoplasm Staging; D015513:Oncogene Proteins; D010190:Pancreatic Neoplasms / Q000097:blood* / Q000175:diagnosis*; D011506:Proteins / Q000378:metabolism; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012737:Sex Factors
chemical_list: C502296:AGR2 protein, human; D014408:Biomarkers, Tumor; D018395:CA-19-9 Antigen; D002352:Carrier Proteins; D051847:Lithostathine; D008565:Membrane Proteins; D009088:Mucoproteins; D015513:Oncogene Proteins; D011506:Proteins; C497618:REG1B protein, human; C107454:Sycn protein, rat; D000594:Amino Acid Oxidoreductases; C119091:LOXL2 protein, human