Trial of a Gastrin Receptor Antagonist in Barrett's Esophagus

Inclusion Criteria:

* Age \>= 18 years, with histologically confirmed diagnosis of Barrett's Esophagus without dysplasia
* Minimum of 1 cm circumferential Barrett's mucosa on endoscopy or at least 2 cm maximal contiguous extent of Barrett's mucosa
* Proton pump inhibitor use at least once daily for at least twelve months prior to enrolment, and stable dose of PPI for the three months before enrolment
* ECOG performance status ≤ 2 and Karnofsky ≥ 60%
* Normal organ and marrow function
* Use of adequate contraception during the study
* Willingness to comply with all treatment and follow up procedures
* Ability to understand and the willingness to sign a written informed consent document
* Up to date with all age appropriate cancer screening tests, as per American Cancer Society guidelines

Exclusion Criteria:

* Histologically confirmed BE with high grade dysplasia, invasive carcinoma of the esophagus, low grade dysplasia
* Prior endoscopic therapy for BE
* History of esophageal or gastric surgery
* History of atrophic gastritis, pernicious anemia, or Zollinger-Ellison syndrome
* Participation in a trial of an investigational medicinal product within the previous 28 days
* Prolonged QTc interval \>450 msec
* History of allergic reactions attributed to compounds of similar chemical composition to YF476
* History of baseline findings of: diabetes mellitus requiring insulin therapy; pancreatitis; hepatitis B, hepatitis C or HIV; malabsorption syndrome or inability to swallow or retain oral medicine; major surgery ≤ 28 days prior to enrollment; ECOG performance status ≥ 2; or another cancer within 3 years except for basal carcinoma of the skin or cervical carcinoma in situ; any clinically significant and uncontrolled major morbidity
* Certain medicines and herbal remedies taken during the 7 days before the start of study drug
* Has evidence of cancer at the time of enrolment, or has surveillance tests planned within 21 weeks after enrollment