Inclusion Criteria:

• Diagnosis of PD consistent with United Kingdom Brain Bank Criteria or the Movement Disorder Society Research Criteria for the Diagnosis of Parkinson’s Disease, with bradykinesia and sequence effect being present and prominent motor asymmetry (if no rest tremor).
• DaTscan demonstrating a reduction in dopamine transporter binding in the striatum consistent with the diagnosis of PD.
• Men or women at least 30 years of age and no more than 80 years of age (inclusive) at screening.
• Modified Hoehn and Yahr stage ≤ 2.5.
• Montreal Cognitive Assessment ≥ 24. 
• If of reproductive potential, willing and able to use a highly effective form of birth control during the study and for 30 days following last dose of study material. Examples of highly effective forms of birth control are:
  • Surgical sterility (via vasectomy, hysterectomy, or bilateral tubal ligation) or postmenopausal status in females;
  • Sexual partner who is sterile or of the same sex;
  • Implants of levonorgestrel in females;
  • Oral contraceptive (combined or progesterone only) in females when combined with a chemical or physical barrier method;
  • Double-barrier method (any combination of physical and chemical methods);
  • Intrauterine device in females, or other method with published data showing that the lowest expected failure rate is less than 1% per year.
  • Able and willing to comply with scheduled visits, treatment plan, laboratory tests, and other study-related procedures to complete the study.
  • Investigational Review Board-approved consent form signed and dated by subject.
  • Assessed as an appropriate and suitable candidate by the Enrollment Authorization Committee (EAC).

Exclusion Criteria:

• Diagnosis of secondary or atypical Parkinsonism.
• Onset of any parkinsonian motor sign or symptom > 5 years before Screening Visit.
• Previous surgical procedure for PD.
• Past treatment with dopaminergic agents (e.g., levodopa), dopaminergic agonists or antagonists, or monoamine oxidase-B inhibitors for more than 28 days or treatment with any of these medications within 14 days before screening, with the exception of treatment with irreversible monoamine oxidase-B inhibitors (e.g., selegiline), which must be discontinued for at least 90 days before screening.
• Any subject who, in the judgment of the investigator, is likely to require dopaminergic treatment during the duration of the study.
• Clinically significant medical, surgical, psychiatric, or laboratory abnormality that, in the judgment of the investigator, is likely to adversely affect subject’s risk-benefit or interfere with study compliance or assessment of safety or efficacy.
• Subject has an ECG or clinical evidence of potentially unstable heart disease, including the following:
  • QTcF > 470 msec females; > 450 msec males;
  • Complete right or left bundle branch block;
  • Ischemia or myocardial infarct within 1 year prior to the Screening Visit;
  • Clinically significant atrial or ventricular dysrhythmia; the heart must be in predominantly normal sinus rhythm;
  • Second or third degree atrioventricular block;
  • Heart failure of New York Heart Association classification III or greater;
  • Serious cardiomyopathy or cardiac structural abnormality;
  • Symptomatic coronary artery or ischemic cardiac disease;
  • Any other cardiac condition that the investigator feels may predispose the subject to ischemia or arrhythmia.
• Current (or within past 12 months) diagnosis or history of substance abuse (excluding nicotine or caffeine) by Diagnostic and Statistical Manual of Mental Disorders 5 criteria, or positive urine drug screen for tetrahydrocannabinol (THC) or any drugs that may affect subject safety or interfere with efficacy assessments.
• Medical or recreational use of marijuana or THC-containing compounds within 3 months of the Screening Visit.
• Active suicidal ideation within 1 year prior to Screening Visit as determined by a positive response to Question 4 or 5 on the C-SSRS.
• Currently active major depression as determined by BDI-II score of >19.
• Currently lactating or pregnant, or planning to become pregnant during the study.
• Current participation in another interventional, investigational clinical study and/or receipt of any investigational drug within 90 days prior to screening.
• Alanine aminotransferase or aspartate aminotransferase levels greater than 2 times the upper limit of normal (ULN) or Child-Pugh Category B or C.
• Amylase or lipase greater than 1.5 times the ULN.
• Significant renal impairment as determined by estimated glomerular filtration rate (Chronic Kidney Disease Epidemiology Collaboration 2009 equation) ≤ 50 mL/min.
• Personal or family history of thyroid malignancy or multiple endocrine neoplasia (MEN syndrome).
• History of pancreatitis.
• Presence of gastroparesis or other severe gastrointestinal disease or abnormality.
• Any subject with current diagnosis or history of type 1 or type 2 diabetes, or screening HbA1c result ≥ 6.0%.
• Thyroid-stimulating hormone 1.3 times the ULN
• Body mass index < 18.5 kg/m^2.
• History of inability to complete DaTscan or intolerance of DaTscan.
• History of hypersensitivity to the study material excipients and/or polyethylene glycol; or a history of drug or other allergy that, in the opinion of the investigator, contraindicates participation.
• History of anaphylaxis to any substance.
• Previous randomization into this study.
• Prior exposure to exenatide or other GLP-1R agonists.
• Prior exposure to NLY01.