Safety and Tolerability of Tozadenant as Adjunctive Therapy in Levodopa-Treated Patients With Parkinson's Disease.

A Multicenter, Open-Label Study to Evaluate the Safety and Tolerability of Tozadenant as Adjunctive Therapy in Levodopa-Treated Patients With Parkinson's Disease Experiencing End of Dose "Wearing-Off"

Phase 3, international, multicenter, open-label 12 month safety study.

Each patient will participate for up to 52 weeks, which includes a Screening Period, followed by a Baseline Visit and open-label treatment for 1 year with a safety Follow-up 4 weeks after the last treatment.

• Screening Period: up to 6 weeks.
• Open-Label Treatment Period: 52 weeks (1 year)
• 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 (except DBS if electrode placement has been performed over 12 months prior to screening)
• 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