Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of GT-02287 in Parkinson's Disease

The main goal of this clinical trial is to learn about the safety and tolerability of GT-02287. The questions it aims to answer are: * What medical problems do participants have when taking GT-02287? * How is GT-02287 absorbed, distributed, and removed from the body of participants over time (pharmacokinetics)? * Are there any biological effects of GT-02287 in blood and in cerebrospinal fluid that could be beneficial for people with Parkinson's disease? Participants will: * visit the clinic to assess if they qualify for the study (30-day Screening Period) * if eligible, receive GT-02287 once a day every day for 90 days (90-day Open Label Treatment period) * visit the clinic the first day of treatment, after the first 2 weeks of treatment, and every month during the 90-day Treatment Period. * visit the clinic to assess how they are doing 14 days after the end of GT-02287 treatment (14-day Follow-Up Period).

This Phase 1b, 3-month, multicenter, open-label study of GT-02287 in participants with Parkinson's Disease with or without GBA1 mutations. The primary objective of the study is to evaluate the safety and tolerability of GT-02287. The study will also investigate pharmacokinetics (PK) and explore pharmacodynamic parameters in blood and CSF and effect of GT-02287 on scores from selected clinical scales. Approximately 20 participants will be enrolled to result in approximately 15 evaluable participants. All participants will receive an oral dose of GT-02287 of 13.5 mg/kg/day (plus/minus 2 mg/kg/day) once a day for 90 days.