Phase Ⅲ Clinical Trial to Evaluate the Efficacy and Safety of TJ0113 Capsules in Patients With Early-Onset Parkinson's Disease

This study is a randomized, double-blind, multicenter, placebo-controlled Phase III clinical trial designed to evaluate the efficacy, safety, and Pop PK characteristics of TJ0113 Capsules in treating EOPD patients. This study plans to enroll approximately 300 EOPD participants, who will be randomized in a 1:1 ratio to two cohorts (Cohort 1: 200 mg dose group; Cohort 2: 400 mg dose group). Within each cohort, successfully screened participants will be stratified by stable use of dopamine receptor agonists (Yes vs. No) and stable use of Monoamine Oxidase B (MAO-B) inhibitors (Yes vs. No), and within each stratum, randomized in a 2:1 ratio to the TJ0113 Capsules group and the placebo group, with approximately 100 assigned to the TJ0113 Capsules group and approximately 50 assigned to the placebo group. In this trial, the sample size for the TJ0113 Capsules 200 mg group, TJ0113 Capsules 400 mg group, and placebo group will each be approximately 100 participants. After randomization, during the double-blind treatment period, participants will receive continuous oral administration of TJ0113 Capsules or placebo for 26 weeks. After the double-blind treatment ends, participants will enter the open-label treatment period. During the open-label treatment period, all participants will receive oral TJ0113 Capsules for 26 weeks, and the dose of TJ0113 Capsules will be consistent with the dose of the investigational product taken by the participant during the double-blind treatment period (regardless of whether they took TJ0113 Capsules or placebo during the double-blind treatment period). After the open-label treatment period ends, participants will continue to receive a safety follow-up for 1 week (telephone follow-up). From the screening period to the end of the double-blind treatment period, all participants must maintain their original background anti-PD medication regimen unchanged; from the open-label treatment period to the end of the study, changes to the dose of stably received anti-PD medications are discouraged, but if necessary, the dose may be adjusted at the discretion of the investigator.

Inclusion Criteria: 1. Participants who voluntarily participate in the clinical trial, and have signed the ICF, are able to understand and follow the study protocol, willing to visit the study site on time, fully understand the content, process and potential adverse reactions of the study, and indicate the date of signing the ICF; 2. Male or female aged 18 to 80 years (inclusive) at the time of signing the ICF; 3. Meets the 2015 International Parkinson and Movement Disorder Society (MDS) diagnostic criteria for primary PD\[1\] or the 2016 Chinese diagnostic criteria for Parkinson's disease\[13\]; with an age of onset ≤50 years, diagnosed as EOPD; 4. Able to cooperate in completing the "off" time records in the diary card; 5. Modified Hoehn-Yahr stage 1\~2.5 (inclusive) in the "off" state at screening; 6. Has been stably receiving anti-PD treatment before baseline and agrees to keep the original anti-PD medication unchanged during the trial; at the time of randomization, the investigator judges that the current treatment regimen has achieved optimal disease management status; -"Stably receiving anti-PD treatment" is defined as: 1) Must use levodopa, may be combined with other anti-PD medications; 2) The type and name of anti-PD medications used by the participant have remained unchanged for at least 3 months prior to the baseline visit, and the dose has remained unchanged for at least 1 month prior to the baseline visit; 3) In this trial: No planned dose regimen adjustments during the double-blind treatment period; changes to the dose of stably received anti-PD medications are discouraged during the open-label treatment period, but if necessary, the dose may be adjusted at the discretion of the investigator. 7. MDS-UPDRS Part III score ≥22 in off-anti-PD medication state at screening; 8. Participants of childbearing potential (including spouses of male participants) who have no childbearing or sperm donation plan from the end of the screening period to within 6 months after the last dose and are willing to use at least one effective method (see Appendix I for details) for contraception. Exclusion Criteria: 1. Presence of any medical condition that may interfere with full participation in the study, including but not limited to the following: medical history of epilepsy or any complications, medical history of hemolytic anemia, pulmonary embolism, respiratory depression, active psychiatric disease, or malignancy; positive tumor marker detection results at screening and judged by the investigator to be clinically significant; 2. Participants who have experienced a New York Heart Association (NYHA) Class III or above congestive heart failure, unstable angina pectoris, acute myocardial infarction, hemorrhagic stroke (stroke), and ischemic stroke (including transient ischemic attack) within 6 months before screening; or those who have undergone any percutaneous coronary intervention or coronary artery bypass grafting, heart valve repair/replacement; or those with severe arrhythmia as judged by the investigator at the time of screening; 3. A personal or family history of long QT syndrome, a family history of sudden death in first-degree relatives (parents, offspring, and siblings) before the age of 40; and/or a personal history of unexplained syncope within 1 year prior to screening; and/or QTcF \>450 ms (male) or QTcF \>470 ms (female) based on resting ECG results at screening; 4. Participants with unstably controlled hypertension at screening, defined as the systolic blood pressure ≥ 160 mmHg and/or the diastolic blood pressure ≥ 100 mmHg (verify before randomization); 5. Participants with symptomatic orthostatic hypotension at screening, or who experiences a decrease in systolic blood pressure of ≥ 30 mmHg or a decrease in diastolic blood pressure of ≥ 15 mmHg within 3 minutes when changing from the supine to the standing position (verify before randomization); 6. Atypical Parkinsonism (e.g., multiple system atrophy, progressive supranuclear palsy, etc.), or secondary parkinsonism with clear etiologies such as drug-induced, vascular, toxic, metabolic, infectious, or traumatic brain injury; 7. Participants who have clinically significant hepatic insufficiency which is defined as the total bilirubin (TBIL) \> 2 × upper limit of normal (ULN) or alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST) \> 2 × ULN; 8. Participants with clinically significant renal insufficiency (creatinine clearance \[Ccr\] \