Clinical Study to Evaluate XS411 in Treatment of Early-onset Parkinson's Disease

This study is a Phase I/II clinical study to evaluate the safety, tolerability, and efficacy of XS411 in the treatment of EOPD. The study consists of two phases: Phase I and Phase II. Phase I study is planned to be conducted in patients with EOPD, using a single-arm, open-label, traditional " 3+3 " dose-escalation design, aiming to investigate the safety, tolerability and preliminary efficacy of XS411 in the treatment of EOPD and to determine the RP2D. Phase I study enrolls 6-12 patients with EOPD. Two dose cohorts (3-6 patients/dose cohort) are planned: 9×10⁶ cells /patient and 1.8 ×10⁷ cells /patient. Each participant will receive a single injection of XS411. Each participant in each dose cohort will be observed for at least 28 days after dosing . If no DLTs occur and the investigator has no other safety concerns for that participant, the next participant in that dose cohort will be enrolled. Phase II study is planned for patients with EOPD, using a randomized, double-blind, sham-controlled, parallel-group design . The study will investigate the efficacy and safety of XS411 in the treatment of EOPD . Phase II study currently plans to enroll 81 patients with EOPD. The patients will be randomly assigned in a 2:1 ratio to either the experimental or control group. Participants in the experimental group will receive a single injection of XS411 in combination with an immunosuppressant at the RP2D determined during the Phase I dose-escalation phase (which may be adjusted based on the Phase II study results). The control group will receive a sham procedure in combination with an immunosuppressant sham.