Inclusion Criteria:

1. Is male or female and aged 18 to 80 years, inclusive.
2. In the opinion of the investigator, the participant is capable of understanding and complying with protocol requirements.
3. The participant or, when applicable, the participant's legally acceptable representative signs and dates a written, informed consent form and any required privacy authorization prior to the initiation of any study procedures.
4. Has a history of initial complete eradication of intestinal metaplasia (CEIM) following radiofrequency ablation (RFA) for Barrett's esophagus with high-grade dysplasia within the past 3 years.
5. Had attained CEIM within 12 months of receiving his or her first RFA treatment.
6. Has endoscopic and histologic confirmed evidence of CEIM prior to randomization.
7. A male participant who is nonsterilized and sexually active with a female partner of childbearing potential agrees to use adequate contraception from signing of informed consent throughout the duration of the study and for 12 weeks after last dose.
8. A female participant of childbearing potential who is sexually active with a nonsterilized male partner agrees to use routinely adequate contraception from signing of informed consent throughout the duration of the study.

Exclusion Criteria:

1. Has evidence of cardiovascular, pulmonary, central nervous system, hepatic, hematopoietic, renal, metabolic, endocrine or gastrointestinal disease, or serious allergy, asthma, or allergic skin rash that suggests clinically significant, uncontrolled underlying disease or condition (other than the disease being studied), which may impact the ability of the participant to participate or potentially confound the study results.
2. Had previous ablative therapy with a modality other than RFA for Barrett's esophagus (photodynamic therapy, multipolar electrical coagulation, argon plasma coagulation, or laser treatment) with the exception of a single treatment with argon plasma coagulation for focal residual disease following otherwise successful RFA therapy.
3. Has a co-existing disease affecting the esophagus (eg, erosive esophagitis, esophageal varices, scleroderma, viral or fungal infection, or esophageal stricture), history of radiation therapy or cryotherapy to the esophagus, caustic or physiochemical trauma such as sclerotherapy to the esophagus.
4. Has a known history of eosinophilic esophagitis or endoscopic findings suggestive of eosinophilic esophagitis.
5. Has active gastric or duodenal ulcers within 4 weeks prior to Day -1.
6. Has any finding in his/her medical history, physical examination, or safety clinical laboratory tests giving reasonable suspicion of underlying disease that might interfere with the conduct of the trial.
7. Has a history of hypersensitivity or allergies to dexlansoprazole or any component of dexlansoprazole or any proton pump inhibitor (PPI) (including lansoprazole, omeprazole, rabeprazole, pantoprazole, or esomeprazole) or antacid.
8. Is required to take excluded medications or it is anticipated that the participant will require treatment with at least one of the disallowed concomitant medications during the study evaluation period as specified in the Excluded Medications and Treatments Section..
9. Has a history of malignant disease (except basal cell carcinoma) within 5 years prior to Screening.
10. Has a condition that may require inpatient surgery during the course of the study.
11. Requires dilatation of esophageal strictures and/or strictures preventing passage of the endoscope during the Screening endoscopy. Schatzki's ring (a ring of mucosal tissue near the lower esophageal sphincter) is acceptable.
12. Is known to have acquired immunodeficiency syndrome.
13. Has current or clinical history of Zollinger-Ellison syndrome or other hypersecretory condition.
14. Has a history of gastric, duodenal or esophageal surgery except simple oversew of an ulcer. A history of gastric tube and/or percutaneous endoscopic gastrostomy (PEG) placement is allowed.
15. Had an acute upper gastrointestinal hemorrhage within 4 weeks prior to endoscopy.
16. Has donated or lost ≥300 mL blood volume, undergone plasmapheresis, or has had a transfusion of any blood product within 90 days prior to the first dose of study drug.
17. Has a known history of alcohol abuse or illegal drug use within the past 12 months prior to the first dose of study drug, or is unwilling to agree to abstain from alcohol or illegal drug use throughout the study.
18. If female, the participant is pregnant or lactating or intending to become pregnant before, during or within 30 days after last dose of study medication; or intending to donate ova during such time period.
19. If male, the participant intends to donate sperm during the course of this study or within 30 days after last dose of study drug.
20. Is an immediate family member, study site employee, or is in a dependent relationship with a study site employee who is involved in the conduct of this study or may consent and assent under duress. Students of the institution/research facility who are under the supervision of, or in a subordinate role to, the investigator are also ineligible.
21. In the opinion of the investigator, is unlikely to comply with the protocol requirements or is unsuitable for any other reason.
22. Has been previously randomized in this study and received at least one dose of double blind study drug treatment.
23. Has received any investigational compound within 30 days prior to Screening.