A Study of Oral ARD-101 in Patients With Prader-Willi Syndrome

Inclusion Criteria:

   - Male and female subjects, 17-65 years of age

   - Provide voluntary, written informed consent (parent(s) / legal guardian(s) of
   participant); provide voluntary, written assent (participants, as appropriate)

   - PWS due to chromosome 15 micro-deletion, maternal uniparental disomy, or imprinting
   defect, confirmed by fluorescent in situ hybridization, chromosomal microarray, and/or
   methylation studies

   - BMI ≥ 18.5 kg/m²

   - A HQ-CT score ≥ 10

   - If a subject has a diagnosis of type 2 diabetes, the following criteria must be met:

      1. Hemoglobin A1c (HbA1c) <7.5% not being managed with insulin. Patients taking
      glucagon-like peptide (GLP)-1 analogues (exenatide or liraglutide) must have been
      on stable dose for greater than 3 months.

      2. Fasting plasma glucose <140 mg/dL during the Screening Period

      3. No history of ketoacidosis or hyperosmolar coma

   - Stable or well-controlled blood pressure (BP) and vital signs. Specifically: Vital
   signs after 5 minutes resting in seated position (feet flat on floor, back supported):

      1. 95 mmHg <160 mmHg

      2. 45 mmHg <100 mmHg

      3. 40 bpm <100 bpm

   - Stable body weight for ~2 months (self or guardian-reported loss/gain within ± 10%)
   prior to enrollment

   - Standard 12-lead ECG parameters after 10 minutes resting in supine position in the
   following ranges; 120 ms <220 ms, QRS <120 ms, QTc ≤430 ms if male, ≤450 ms if
   female and normal ECG tracing unless the Investigator considers an ECG abnormality to
   be not clinically relevant.

   - Parent or guardian is able to communicate well with the investigator, to understand
   and comply with the requirements of the study, and be able to understand and sign the
   written informed consent. Assent is to be provided for the patient who cannot consent
   for himself or herself

   - Results of screening clinical laboratory tests [complete blood count (CBC) with
   differential and platelets and chemistry profile] and vital signs must be within
   normal range or, if outside of the normal range, must be accepted by the investigator
   and sponsor as not clinically significant

   - Females of non-childbearing potential, defined as surgically sterile (status post
   hysterectomy, bilateral oophorectomy, or bilateral tubal ligation) or post-menopausal
   for at least 12 months (and confirmed with a screening FSH level in the
   post-menopausal lab range), do not require contraception during the study. This may
   also apply to subjects with documented hypogonadism with and without estrogen
   replacement therapy as per investigator judgement. All other females of child-bearing
   potential must agree to use contraception as outlined in the protocol

   - Males with female partners of childbearing potential must agree to a double barrier
   method if they become sexually active during the study and for 90 days following the
   study.

   - Patients previously treated with ARD-101 may be re-enrolled based on investigator
   decision and/if at least 3 months time has passed since the last dose.

   - Patients must be on a stable dose of any allowed chronic concomitant medications while
   participating in the study, as described in protocol. This is defined as no changes in
   medication or dose for at least 30 days prior to Day 1 Stable concomitant usage (>3
   months) of medications commonly used in PWS patients are allowed

Exclusion Criteria:

   - Use of weight loss agents, including herbal medication, within 3 months prior to
   enrollment

   - Diagnosis of schizophrenia, bipolar disorder, personality disorder, or other DSM-III
   disorders which the investigator believes will interfere significantly with study
   compliance

   - A PHQ-9 score of ≥10

   - Any suicidal ideation of type 4 or 5 on the C-SSRS

   - Clinically significant illness in the 8 weeks prior to enrollment

   - History of clinically significant bleeding disorders

   - Current, clinically significant liver, renal, pulmonary, cardiac, oncologic, or
   gastrointestinal (GI) disease

   - Diagnosis of type 1 diabetes mellitus or other active endocrine disorders (e.g.,
   Cushing syndrome, or thyroid dysfunction except if on stable adequate thyroid or
   glucocorticoid replacement supplement)

   - Liver disease or liver injury as indicated by abnormal liver function tests, SGOT
   (aspartate aminotransferase (AST)), alkaline phosphatase, or serum bilirubin (> 1.5 x
   upper limit of normal (ULN) for any of these tests) or history of hepatic cirrhosis

   - History or presence of impaired renal function as indicated by clinically
   significantly abnormal creatinine, blood urea nitrogen (BUN), or urinary constituents
   (e.g., albuminuria) or moderate to severe renal dysfunction as defined by the Cockroft
   Gault equation (< 50 mL/min)

   - Significant history of abuse of drugs within 1 year prior to enrollment or a positive
   Drugs of Abuse (DOA) test at screening

   - History of alcohol abuse within 1 year prior to enrollment or currently drinks in
   excess of 21 units per week (3 servings or units/day)

   - Caffeine consumption exceeding 6 cups of caffeinated tea/coffee (or equivalent) per
   day

   - Participation in any clinical study with an investigational drug/device within 1 month
   prior to enrollment

   - Serious adverse reaction or significant hypersensitivity to any drug

   - Clinically significant blood loss or blood donation > 500 mL within 3 months prior to
   enrollment

   - Inadequate venous access

   - History of significant drug hypersensitivity or anaphylaxis

   - Any condition that the investigator or primary physician believes may not be
   appropriate for participating the study