Lenrispodun as Adjunctive Therapy in the Treatment of Patients With Motor Fluctuations Due to Parkinson's Disease

Inclusion Criteria:

1. Male or female between 40 years of age and older

2. Body mass index of 19.0-40.0 kg/m2;

3. Diagnosis of PD that is consistent with the UK Parkinson's Disease Society (UKPDS)Brain Bank diagnostic criteria;

4. Hoehn and Yahr Scale stage classification of 2 or 3 when in the ON state;

5. Have a clinically meaningful response to levodopa (levodopa + DDCI combination)based on Investigator assessment, and meet the following:

6. Have been on a stable and optimal dose of levodopa (levodopa + DDCIcombination: minimum dose of levodopa equivalent to 100 mg three times daily)for at least 4 weeks prior to Screening, and are expected to continue the samedose regimen throughout the Double-blind Treatment Period;

7. If taking other anti-parkinsonian medications (MAO-B [monoamine oxidase B]inhibitor, COMT [catechol-O-methyltransferase] inhibitor, dopamine agonist) inaddition to levodopa, have been on a stable dose for at least 4 weeks prior toScreening and are expected to continue the same dose regimen throughout theDouble-blind Treatment Period;

8. Have wearing-off symptoms and levodopa-induced dyskinesia as per Investigator judgment; 8. Properly complete and return a self-reported home diary for motor function status (Hauser Diary) during the Screening Period, which confirms 3 days (ie, 3 consecutive, 24-hour periods) immediately prior to Baseline, each with at least 2½ hours of OFF time during waking hours.

9. Has a caregiver to assist with study participation, if determined by the Investigator to be necessary.

Exclusion Criteria:

1. Medical history indicating parkinsonism other than idiopathic PD, including but notlimited to, progressive supranuclear gaze palsy, multiple system atrophy,drug-induced parkinsonism, essential tremor, primary dystonia;

2. Has late-stage PD, severe peak-dose dyskinesia, clinically significant end-dose orbiphasic dyskinesia, and/or unpredictable or widely swinging fluctuations in theirsymptoms as assessed by the Investigator;

3. Exhibits clinical signs of dementia as indicated by the Mini-Mental StateExamination, 2nd Edition: Standard Version (MMSE-2:SV) score of ≤ 24;

4. Use of moderate or strong CYP3A4 inhibitors within 5 half-lives of Baseline orCYP3A4 inducers within 2 weeks of Baseline;

5. Daily use of nonsteroidal anti-inflammatory drugs (NSAIDs), with the exception ofacetylsalicylic acid (ASA);

6. Use of MAO-A inhibitors, phosphodiesterase type 5 (PDE5) inhibitors, or alphablockers including tamsulosin, within 5 half-lives of Baseline;