This is a multicenter, randomized, double-blind, placebo-controlled, parallel-group, fixed-dose study in patients with a diagnosis of Parkinson's Disease consistent with the UK Parkinson's Disease Society (UKPDS) Brain Bank diagnostic criteria, who are experiencing wearing off symptoms and levodopa-induced dyskinesia.

The study will be conducted in three periods:

• Screening Period (up to 4 weeks) during which patient eligibility will be assessed;
• Double-blind Treatment Period (4 weeks) in which all patients will be randomized to receive placebo or Lenrispodun 30 mg/day in 1:1 ratio.
• Safety Follow-up Period (1 week) in which all patients will return to the clinic for a safety follow-up visit approximately one week after the last dose of study treatment.

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:

   1. Have been on a stable and optimal dose of levodopa (levodopa + DDCI combination: 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 same dose regimen throughout the Double-blind Treatment Period;
   2. If taking other anti-parkinsonian medications (MAO-B [monoamine oxidase B] inhibitor, COMT [catechol-O-methyltransferase] inhibitor, dopamine agonist) in addition to levodopa, have been on a stable dose for at least 4 weeks prior to Screening and are expected to continue the same dose regimen throughout the Double-blind Treatment Period;

7. 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 not limited 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 or biphasic dyskinesia, and/or unpredictable or widely swinging fluctuations in their symptoms as assessed by the Investigator;
3. Exhibits clinical signs of dementia as indicated by the Mini-Mental State Examination, 2nd Edition: Standard Version (MMSE-2:SV) score of ≤ 24;
4. Use of moderate or strong CYP3A4 inhibitors within 5 half-lives of Baseline or CYP3A4 inducers within 2 weeks of Baseline;
5. Daily use of nonsteroidal anti-inflammatory drugs (NSAIDs), with the exception of acetylsalicylic acid (ASA);
6. Use of MAO-A inhibitors, phosphodiesterase type 5 (PDE5) inhibitors, or alpha blockers including tamsulosin, within 5 half-lives of Baseline;