Efficacy and Safety of Vonoprazan Compared to Lansoprazole in Participants With Erosive Esophagitis

Inclusion Criteria:

1. The participant is ≥18 years of age at the time of informed consent signing.
2. In the opinion of the investigator or subinvestigators, the participant is capable ofunderstanding and complying with protocol requirements.
3. The participant signs and dates a written, informed consent form and any requiredprivacy authorization prior to the initiation of any study procedures. The participantis informed of the full nature and purpose of the study, including possible risks andside-effects. The participant has the ability to cooperate with the investigator.Ample time and opportunity should be given to read and understand verbal and/orwritten instructions.
4. The participant is found to have endoscopically confirmed EE of LA ClassificationGrades A to D during the Screening Period (Visit 1) as assessed by a centraladjudicator. The target number of participants with LA classification Grade C or Dwill be approximately 30% of the total number of participants (300 total). Enrollmentof EE participants with Grade A or B will end when the number of participants withGrade A or B EE is approximately 700 or 70% of the total planned number ofparticipants. Given the invasive nature of an endoscopy, any endoscopic confirmationperformed in a routine clinical setting before signing the informed consent will beacceptable to use for the purpose of fulfilling the screening requirement if all ofthe following apply: (1) appropriate endoscopy pictures were taken; (2) appropriategastric biopsy samples were taken; (3) the endoscopy pictures can be sent to thecentral adjudicator via the adjudication systems; and (4) all screening procedures (including the completion of adjudication) AND randomization can be completed within a 7-day period after the date of the endoscopy.
5. A female participant of childbearing potential who is or may be sexually active with anonsterilized male partner agrees to routinely use adequate contraception from thesigning of informed consent until 4 weeks after the last dose of study drug.

Exclusion Criteria:

1. The participant's endoscopic examination for entering this study fails to confirm EEwithin 7 days (no later than 10 days on rare occasion with sponsor approval) prior torandomization.
2. The participant is determined to be positive for Helicobacter pylori (HP) or has hadan HP infection within 45 days of randomization.
3. The participant has endoscopic Barrett's esophagus (>1 cm of columnar-lined esophagus)and/or definite dysplastic changes in the esophagus.
4. The participant has any other condition affecting the esophagus, includingeosinophilic esophagitis; esophageal varices; viral or fungal infection; esophagealstricture; a history of radiation therapy, radiofrequency ablation, endoscopic mucosalresection, or cryotherapy to the esophagus; or any history of caustic orphysiochemical trauma (including sclerotherapy or esophageal variceal band ligation).However, participants diagnosed with Schatzki's ring (mucosal tissue ring around loweresophageal sphincter) are eligible to participate.
5. The participant has scleroderma (systemic sclerosis).
6. The participant has a history of surgery or endoscopic treatment affectinggastroesophageal reflux, including fundoplication and dilation for esophagealstricture (except Schatzki's ring) or a history of gastric or duodenal surgery (exceptendoscopic removal of benign polyps).
7. The participant has an active gastric or duodenal ulcer at the start of the ScreeningPeriod. Additionally, participants with gastric or duodenal erosions are permitted toparticipate.
8. The participant has received any investigational compound (including those in postmarketing studies) within 30 days prior to the start of the Screening Period. Aparticipant who has been screen failed from another clinical study and who has notbeen dosed may be considered for enrollment in this study.
9. The participant is a study site employee, an immediate family member, or is in adependent relationship with a study site employee who is involved in the conduct ofthis study (eg, spouse, parent, child, sibling) or who may have consented underduress.
10. The participant has cutaneous lupus erythematosus or systemic lupus erythematosus.
11. The participant has had clinically significant upper or lower gastrointestinalbleeding within 4 weeks prior to randomization.
12. The participant has Zollinger-Ellison syndrome or other gastric acid hypersecretoryconditions.
13. The participant has a history of hypersensitivity or allergies to vonoprazan (including the formulation excipients: D-mannitol, microcrystalline cellulose,hydroxypropyl cellulose, fumaric acid, croscarmellose sodium, magnesium stearate,hypromellose, macrogol 8000, titanium oxide, or red or yellow ferric oxide), PPIs, orany excipients used in the 13C-urea breath test: mannitol, citric acid, or aspartame.Skin testing may be performed according to local standard practice to confirmhypersensitivity.
14. The participant has a history of alcohol abuse, illegal drug use, or drug addictionwithin the 12 months prior to screening, or regularly consumes >21 units of alcohol (1unit = 12 oz/300 mL beer, 1.5 oz/25 mL hard liquor/spirits, or 5 oz/100 mL wine) perweek based on self-report. Participants must have a negative urine drug screen atscreening.
15. The participant is taking any excluded medications or treatments.
16. If female, the participant is pregnant, lactating, or intending to become pregnantbefore, during, or within 4 weeks after participating in this study; or intending todonate ova during such time period.
17. The participant has a history or clinical manifestations of significant centralnervous system, cardiovascular, pulmonary, hepatic, renal, metabolic, othergastrointestinal, urological, endocrine, or hematological disease that, in the opinionof the investigator, would confound the study results or compromise participantsafety.
18. The participant requires hospitalization or has surgery scheduled during the course ofthe study or has undergone major surgical procedures within 30 days prior to theScreening Visit.
19. The participant has a history of malignancy (including MALToma) or has been treatedfor malignancy within 5 years prior to the start of the Screening Period (Visit 1). (The participant may be included in the study if he/she has cured cutaneous basal cellcarcinoma or cervical carcinoma in situ).
20. The participant has acquired immunodeficiency syndrome or human immunodeficiency virusinfection, or tests positive for the hepatitis B surface antigen, hepatitis C virus (HCV) antibody, or HCV RNA. However, participants who test positive for HCV antibodybut negative for HCV RNA are permitted to participate.
21. The participant has any of the following abnormal laboratory test values at the startof the Screening Period:
22. Creatinine levels: >2 mg/dL (>177 μmol/L)
23. Alanine aminotransferase or aspartate aminotransferase >2 × the upper limit ofnormal (ULN) or total bilirubin >2 × ULN.