To Evaluate the Safety and Efficacy of RP902 Tablets

The purpose of the study is to evaluate the preliminary efficacy of RP902 Tablets in participants with Alzheimer's disease (AD)-derived mild cognitive impairment (MCI) and provide a design basis for the Phase III study. This Phase II study plans to enroll 360 participants and will be conducted at approximately 50 sites in China. The study consists of a Screening Period (up to 4 weeks) and a double-blind treatment period (48 weeks). After completing the 48-week double-blind treatment period, participants may choose to continue into an extension treatment period (96 weeks) or undergo safety follow-up (4 weeks after the last dose).

Inclusion Criteria: * Voluntary participation and signed informed consent form. * Junior high school graduation or above, capable of completing cognitive function assessments and other tests specified in the protocol. * Meet the core clinical diagnostic criteria for mild cognitive impairment (MCI) of the National Institute on Aging-Alzheimer's Association (NIA-AA) (2024). * Mini-Mental State Examination (MMSE) score ≥ 24; Clinical Dementia Rating-Global Score (CDR-GS) = 0.5, with memory score ≥ 0.5. * 17-item Hamilton Depression Rating Scale (HAMD) total score ≤ 10. * Hachinski Ischemic Score (HIS) total score ≤ 4. Exclusion Criteria: * Dementia caused by other etiologies. * Neurological diseases other than Alzheimer's Disease (AD). * Positive hepatitis B surface antigen (HBsAg) and/or hepatitis B core antibody (HBcAb) with positive HBV-DNA copy number (above upper limit of normal range); positive hepatitis C virus antibody (HCV Ab) with positive HCV RNA; positive human immunodeficiency virus antibody (HIV Ab); positive Treponema pallidum antibody (TP Ab). * Active systemic bacterial, viral, fungal or parasitic infection, or other clinically significant active infections deemed unsuitable by the investigator. * Male: QTcF \> 450 ms; Female: QTcF \> 470 ms, or other clinically significant abnormal electrocardiogram deemed unsuitable. * Severe or poorly controlled cardiovascular, respiratory, digestive, urinary, hematological, endocrine, or neurological diseases (except AD) within 6 months prior to screening visit. * History of active peptic ulcer, inflammatory bowel disease, or other severe gastrointestinal diseases affecting drug absorption within 6 months prior to screening visit; or history of gastrointestinal bleeding, perforation or gastrointestinal surgery within 5 years (excluding appendectomy, polypectomy, hemorrhoid surgery). * Malignant tumor diagnosed within 3 years prior to screening (excluding cured basal cell carcinoma of the skin, squamous cell carcinoma of the skin, and radically resected carcinoma in situ). * Participation in other clinical trials within 3 months prior to randomization; subjects in non-interventional observational studies may be included if judged by the investigator to have no interference with the safety and efficacy of the study drug. * History of alcohol abuse or drug abuse within 1 year prior to screening visit. * History of severe drug allergy or multiple drug allergies. * Lactating women. * Other conditions deemed unsuitable for the study by the investigator. * Trial Groups