Safety and Efficacy Study of Tozadenant to Treat End of Dose Wearing Off in Parkinson's Patients

A Multicenter, Randomized, Double-Blind, Placebo-Controlled Study to Determine the Efficacy and Safety of Tozadenant as Adjunctive Therapy in Levodopa-Treated Patients With Parkinson's Disease Experiencing End of Dose "Wearing-Off" (TOZ-PD)

Phase 3, international, multicenter, randomized, double-blind, placebo-controlled, parallel-group, 3-arm safety and efficacy study (Part A) with an open-label phase (Part B).

During Part A, each patient will participate for up to 30 weeks, which includes a Screening Period of 1 to ≤ 6 weeks, followed by a Baseline Visit and 24 weeks of double-blind treatment:

• Screening Period: 1 - 6 weeks.
• Double-Blind Treatment Period: 24 weeks.

After completion of Part A, patients will continue in Part B for an additional 56 weeks:

• Open-Label Treatment Period: 52 weeks.
• Post-Treatment Safety Follow Up: 4 weeks.

Inclusion Criteria:

• Patient understands study requirements and has given his/her written informed consent on an Institutional Review Board (IRB) or Independent Ethics Committee (IEC) approved consent form.
• Parkinson's disease diagnosis consistent with UK Parkinson's Disease Society Brain Bank Diagnostic criteria
• Minimum of 3 years since diagnosis.
• Meet Hoehn and Yahr PD stage
• Good response to levodopa
• Stable regimen of anti-PD medications
• Patients must have been taking a levodopa-containing anti-PD medication continuously for at least the previous 12 months
• Patient has documented a minimum amount of Off time.
• If of childbearing potential (male and female) must use an acceptable method of contraception

Exclusion Criteria:

• Previous tozadenant study participation
• Current or recent participation in another study.
• Secondary or atypical parkinsonism
• Neurosurgical intervention for PD
• Patient is taking apomorphine, budipine, istradefylline, tolcapone, or DUOPA™/Duodopa®
• Treatment with excluded medications
• Untreated or uncontrolled hyperthyroidism or hypothyroidism
• Clinically significant out-of-range laboratory
• MMSE out of range
• Current episode of major depression (stable treatment for depression is permitted).
• Recent suicide attempt or suicidal ideation type 4 or type 5 of the Columbia-Suicide Severity Rating Scale (C-SSRS)
• Women lactating or pregnant
• Hypersensitivity to any components of tozadenant or excipients
• Abnormal findings on the physical or neurological examination, or medical history that would make the patient unsuitable for the study
• History of hepatitis or cholangitis