Intervention: Vonoprazan
Trial phase: Phase 4
ATC code: A02BC08 | A02BD14 | A02BD15
SMILES: CNCc1cc(-c2ccccc2F)n(S(=O)(=O)c2cccnc2)c1
Sex: All
Age groups: Adult | Older Adult
Healthy volunteers: No
Participants at risk: 139
Group description: Vonoprazan 20 mg administered orally once daily in the healing phase, after that Vonoprazan 10 mg (as the initial dose and adjusted to Vonoprazan 10 mg or 20 mg) administered orally once daily in the maintenance phase.
Eligibility criteria:
Inclusion Criteria

Healing Phase:

Participants endoscopically diagnosed with EE of grades A to D by the LA Classification Grading System at the start of treatment (Week 0 of the healing phase)
Participants with H. pylori negative
Participants who, in the opinion of the principal investigator or investigator, are capable of understanding the content of the clinical research and complying with the research protocol requirements.
Participants who can sign and date an informed consent form and information sheet prior to the conduction of the clinical research procedures.
Male or female participants aged 20 years or older at the time of informed consent

Therapeutic category: Ambulatory

Maintenance Phase:

Participants who have endoscopically confirmed EE healing* (mucous membrane disorder is not observed) at completion of the healing phase (Week 4 or 8 of the healing phase)

* Participants who are classified as grade 0 according to severity classification of EE (See Table 9.b)

Participants who have been determined to be appropriate as subjects for maintenance treatment of EE by the principal investigator or investigator

Exclusion Criteria:

Healing Phase:

Participants with concurrent peptic ulcer (except scarred stage) or Zollinger-Ellison syndrome
Participants who received treatment with PPIs (including vonoprazan) within 4 weeks (Week -4 to Week 0) prior to the start of healing phase (Week 0 of the healing phase)
Participants with a history of H. pylori eradication.
Participants who have received surgery or treatment affecting gastroesophageal reflux (fundoplication or dilation for esophageal stenosis [excluding Schatzki's ring], etc.)
Participants with an esophagus-related complication (eosinophilic esophagitis, esophageal varices, scleroderma, viral or fungal infection, esophageal stenosis, etc.), a history of radiotherapy or cryotherapy of the esophagus, a caustic or physiochemical trauma (esophageal sclerotherapy, etc.). However, participants with Schatzki's ring (mucosal tissue ring around inferior esophageal sphincter) or Barrett's esophagus are allowed to be included.
Participants with clinically apparent hepatic impairment (e.g., AST or ALT levels at the time of informed consent: >1.5 times the upper limit of normal (ULN).
Participants with renal impairment or renal failure [creatinine clearance (CCr) ˂30 mL/min, etc.]
Participants with a history of hypersensitivity or allergy for PPIs.
Participants with a history of gastrectomy, gastrointestinal resection, or vagotomy
Participants with a malignant tumor
Participants who are pregnant, breast-feeding, possibly pregnant, or planning to become pregnant
Participants with one of the diseases listed under administration contraindication in the vonoprazan or lansoprazole package insert
Participants planning to take prohibited concomitant medications during the research period
Participants participating in other clinical studies

Participants who have been determined to be inappropriate as subjects in the study by the principal investigator or investigator

Maintenance Phase:

Participants who have taken PPIs other than the study drug or the control drug during the healing phase
Participants who have been determined to be inappropriate as subjects in the study by the principal investigator or investigator