title: Detection of Sessile Serrated Adenomas in the Proximal Colon Using Wide-Field Fluorescence Endoscopy.
abstract: Many cancers in the proximal colon develop via from sessile serrated adenomas (SSAs), which have flat, subtle features that are difficult to detect with conventional white-light colonoscopy. Many SSA cells have the V600E mutation in BRAF. We investigated whether this feature could be used with imaging methods to detect SSAs in patients.
  
  
  
  We used phage display to identify a peptide that binds specifically to SSAs, using subtractive hybridization with HT29 colorectal cancer cells containing the V600E mutation in BRAF and Hs738.St/Int cells as a control. Binding of fluorescently labeled peptide to colorectal cancer cells was evaluated with confocal fluorescence microscopy. Rats received intra-colonic 0.0086 mg/kg, 0.026 mg/kg, or 0.86 mg/kg peptide or vehicle and morbidity, mortality, and injury were monitored twice daily to assess toxicity. In the clinical safety study, fluorescently labeled peptide was topically administered, using a spray catheter, to the proximal colon of 25 subjects undergoing routine outpatient colonoscopies (3 subjects were given 2.25 μmol/L and 22 patients were given 76.4 μmol/L). We performed blood cell count, chemistry, liver function, and urine analyses approximately 24 hours after peptide administration. In the clinical imaging study, 38 subjects undergoing routine outpatient colonoscopies, at high risk for colorectal cancer, or with a suspected unresected proximal colonic polyp, were first evaluated by white-light endoscopy to identify suspicious regions. The fluorescently labeled peptide (76.4 μmol/L) was administered topically to proximal colon, unbound peptide was washed away, and white-light, reflectance, and fluorescence videos were recorded digitally. Fluorescence intensities of SSAs were compared with those of normal colonic mucosa. Endoscopists resected identified lesions, which were analyzed histologically by gastrointestinal pathologists (reference standard). We also analyzed the ability of the peptide to identify SSAs vs adenomas, hyperplastic polyps, and normal colonic mucosa in specimens obtained from the tissue bank at the University of Michigan.
  
  
  
  We identified the peptide sequence KCCFPAQ and measured an apparent dissociation constant of Kd= 72 nM and an apparent association time constant of K = 0.174 min-1(5.76 minutes). During fluorescence imaging of patients during endoscopy, regions of SSA had 2.43-fold higher mean fluorescence intensity than that for normal colonic mucosa. Fluorescence labeling distinguished SSAs from normal colonic mucosa with 89% sensitivity and 92% specificity. The peptide had no observed toxic effects in animals or patients. In the analysis of ex vivo specimens, peptide bound to SSAs had significantly higher mean fluorescence intensity than to hyperplastic polyps.
  
  
  
  We have identified a fluorescently labeled peptide that has no observed toxic effects in animals or humans and can be used for wide-field imaging of lesions in the proximal colon. It distinguishes SSAs from normal colonic mucosa with 89% sensitivity and 92% specificity. This targeted imaging method might be used in early detection of premalignant serrated lesions during routine colonoscopies. ClinicalTrials.gov ID: NCT02156557.
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of Michigan, Ann Arbor, Michigan.
authors.forename: Bishnu P
authors.initials: BP
authors.lastname: Joshi
authors.affiliation: Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan.
authors.forename: Zhenzhen
authors.initials: Z
authors.lastname: Dai
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of Michigan, Ann Arbor, Michigan.
authors.forename: Zhenghong
authors.initials: Z
authors.lastname: Gao
authors.affiliation: Department of Gastroenterology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Jeong Hoon
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of Michigan, Ann Arbor, Michigan.
authors.forename: Navin
authors.initials: N
authors.lastname: Ghimire
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of Michigan, Ann Arbor, Michigan.
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of Michigan, Ann Arbor, Michigan.
authors.forename: Anoop
authors.initials: A
authors.lastname: Prabhu
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of Michigan, Ann Arbor, Michigan.
authors.forename: Erik J
authors.initials: EJ
authors.lastname: Wamsteker
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of Michigan, Ann Arbor, Michigan.
authors.forename: Richard S
authors.initials: RS
authors.lastname: Kwon
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of Michigan, Ann Arbor, Michigan.
authors.forename: Grace H
authors.initials: GH
authors.lastname: Elta
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of Michigan, Ann Arbor, Michigan.
authors.forename: Elena M
authors.initials: EM
authors.lastname: Stoffel
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of Michigan, Ann Arbor, Michigan.
authors.forename: Asha
authors.initials: A
authors.lastname: Pant
authors.affiliation: Division of Gastroenterology, Department of Medicine, VA Palo Alto Health Care System, Palo Alto, California.
authors.forename: Tonya
authors.initials: T
authors.lastname: Kaltenbach
authors.affiliation: Division of Gastroenterology, Department of Medicine, VA Palo Alto Health Care System, Palo Alto, California.
authors.forename: Roy M
authors.initials: RM
authors.lastname: Soetikno
authors.affiliation: Department of Pathology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Henry D
authors.initials: HD
authors.lastname: Appelman
authors.affiliation: Department of Biostatistics, University of Michigan, Ann Arbor, Michigan.
authors.forename: Rork
authors.initials: R
authors.lastname: Kuick
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of Michigan, Ann Arbor, Michigan.
authors.forename: D Kim
authors.initials: DK
authors.lastname: Turgeon
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of Michigan, Ann Arbor, Michigan; Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan; Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan. Electronic address: thomaswa@umich.edu.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Wang
mesh_terms: D000236:Adenoma / Q000000981:diagnostic imaging / Q000235:genetics / Q000473:pathology*; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000000981:diagnostic imaging / Q000235:genetics / Q000473:pathology*; D003111:Colonic Polyps / Q000000981:diagnostic imaging / Q000235:genetics / Q000473:pathology*; D003113:Colonoscopy; D004945:Esophagoscopy; D005260:Female; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D019073:HT29 Cells; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D061848:Optical Imaging; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D051381:Rats
chemical_list: D005456:Fluorescent Dyes; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D016650:Fluorescein-5-isothiocyanate
keywords: Adenoma; Colorectal Cancer; Peptide; Serrated