A Study to Evaluate SAGE-217 in Subjects With Parkinson's Disease

Part A of the study is an open-label design with dosing of Levodopa for 3 days followed by
SAGE-217 for 4 days.

Part B of the study is an open-label design with evening dosing of SAGE-217 for 7 days as an
adjunct to antiparkinsonian agent(s).

Inclusion Criteria:

- Subject has a diagnosis of idiopathic Parkinson's Disease (Hoehn and Yahr Stage 2 or
Stage 3) with a duration of less than 7 years prior to screening [Part A]

- Subject has a diagnosis of idiopathic Parkinson's Disease (Hoehn and Yahr Stage 1-4)
[Part B]

- Subject is on a stable dose (at least 1 month prior to baseline visit) of an
antiparkinsonian agent and is willing to remain on this dose for the duration of the
study

Exclusion Criteria:

- Subject has early (Hoehn and Yahr Stage 1) or advanced (Hoehn and Yahr Stage 4 or
Stage 5) Parkinson's Disease [Part A]

- Subject has advanced (Hoehn and Yahr Stage 5) Parkinson's Disease [Part B]

- Subject with presence of drug-induced parkinsonism, metabolic identified neurogenetic
disorders, encephalitis, or other atypical Parkinsonian syndromes

- Medical history of electroconvulsive therapy or stereotaxic brain surgery for
Parkinson's Disease

- Medical history of suicide attempt within 2 years of screening or current suicidal
ideation

- Medical history of impulse control disorder