Comparison of Keverprazan Hydrochloride-Amoxicillin Dual Therapy and Susceptibility-Guided Quadruple Therapy for Helicobacter Pylori Rescue Treatment

Inclusion Criteria: 1. Male or female participants aged ≥18 years and ≤75 years at the time of signing the informed consent. 2. Participants who have undergone at least one prior standard H. pylori eradication treatment but failed. 3. Current H. pylori infection confirmed by 13C-UBT, or H. pylori culture. 4. Participants who, in the investigator's opinion, are able to understand and comply with the study requirements. 5. Written informed consent and any required privacy authorization documents signed and dated before the initiation of any study procedures. 6. For women of childbearing potential with regular or potential sexual activity with non-sterilized male partners, agreement to use two effective methods of contraception from the time of informed consent until the end of the study. Exclusion Criteria: 1. Presence of gastric or duodenal ulcer with current or recent bleeding as evidenced by endoscopy. 2. Confirmed gastric cancer by endoscopic biopsy. 3. Receipt of any investigational drug (including marketed drugs used in post-marketing studies) within 30 days prior to the screening period. Participants who failed screening and did not receive the investigational drug may be included. 4. Participants who are investigators, relatives of investigators, or otherwise have conflicts of interest or may be under pressure to participate. 5. History of cutaneous or systemic lupus erythematosus. 6. Clinical manifestations of upper or lower gastrointestinal bleeding within 4 weeks prior to randomization. 7. Diagnosis of Zollinger-Ellison syndrome or other gastric acid hypersecretory disorders. 8. Known allergy or hypersensitivity to Keverprazan Hydrochloride (including excipients), PPIs, amoxicillin, clarithromycin, metronidazole, levofloxacin, tetracycline, furazolidone, or excipients in 13C-UBT (mannitol, citric acid, or aspartame). 9. History of alcohol abuse, illicit drug use, or drug addiction within 12 months prior to screening, or weekly alcohol intake exceeding 21 units (1 unit = 12 oz/300 ml beer, 1.5 oz/25 ml spirits, or 5 oz/100 ml wine). 10. Use of antibiotics, bismuth agents, or antiprotozoal drugs within 30 days prior to 13C-UBT, or use of H2 receptor antagonists, PPIs, or interfering drugs (e.g., sodium succinate) within 14 days. 11. Concurrent use of drugs contraindicated with clarithromycin (e.g., colchicine, pimozide, ergot derivatives, tadalafil, terfenadine, astemizole, cisapride, simvastatin, lovastatin, atorvastatin, etc.)..Use of pravastatin, fluvastatin, or rosuvastatin is permitted but should be used with caution. 12. Concurrent use of strong CYP2C19 or CYP3A4 inhibitors or inducers (e.g., fluconazole, fluoxetine, fluvoxamine, ticlopidine, rifampin, ritonavir, itraconazole, ketoconazole, indinavir, nelfinavir, saquinavir, telithromycin). 13. History of surgeries affecting gastric acid secretion, such as gastric resection or vagotomy. 14. Significant central nervous, cardiovascular, hepatic, pulmonary, renal, metabolic, gastrointestinal, urological, reproductive, endocrine, or hematological disorders that may affect the study results or participant safety, as judged by the investigator. 15. History of any malignancy, including MALT lymphoma. 16. Need for hospitalization or surgery during the study or within 30 days prior to screening. 17. Diagnosis of AIDS or HIV infection. 18. Female participants who are pregnant, breastfeeding, planning to become pregnant, or planning to donate eggs during the study or within 4 weeks after the study. 19. Participants with negative H. pylori culture during the screening period. 20. Participants with prior P-CAB plus amoxicillin dual therapy.