Affinity peptide for targeted detection of dysplasia in Barrett's esophagus.

BACKGROUND & AIMS: Dysplasia is a premalignant condition in Barrett's esophagus that is difficult to detect on endoscopy because of its flat architecture and patchy distribution. Peptides are promising for use as novel molecular probes that identify cell surface targets unique to disease and can be fluorescence-labeled for detection. We aim to select and validate an affinity peptide that binds to esophageal dysplasia for future clinical studies.
METHODS: Peptide selection was performed using phage display by removing nonspecific binders using Q-hTERT (intestinal metaplasia) cells and achieving specific binding against OE33 (esophageal adenocarcinoma) cells. Selective binding was confirmed on bound phage counts, enzyme-linked immunosorbent assay (ELISA), flow cytometry, competitive inhibition, and fluorescence microscopy. On stereomicroscopy, specific peptide binding to dysplasia on endoscopically resected specimens was assessed by rigorous registration of fluorescence intensity to histology in 1-mm intervals.
RESULTS: The peptide sequence SNFYMPL was selected and showed preferential binding to target cells. Reduced binding was observed on competition with unlabeled peptide in a dose-dependent manner, an affinity of K(d) = 164 nmol/L was measured, and peptide binding to the surface of OE33 cells was validated on fluorescence microscopy. On esophageal specimens (n = 12), the fluorescence intensity (mean ± SEM) in 1-mm intervals classified histologically as squamous (n = 145), intestinal metaplasia (n = 83), dysplasia (n = 61), and gastric mucosa (n = 69) was 46.5 ± 1.6, 62.3 ± 5.8, 100.0 ± 9.0, and 42.4 ± 3.0 arb units, respectively.
CONCLUSIONS: The peptide sequence SNFYMPL binds specifically to dysplasia in Barrett's esophagus and can be fluorescence labeled to target premalignant mucosa on imaging.