The primary objective is to assess the safety and tolerability of single and multiple oral doses of ERX1000 in obese subjects.

Inclusion Criteria:

• Able to comprehend and willing to sign an informed consent form (ICF) and to abide by the study restrictions.

• Adult females and males, of any race, between 18 and 55 years of age, inclusive, at Screening.

• Females of non-childbearing potential, which is defined as permanently sterile (ie, due to hysterectomy, bilateral salpingectomy, or bilateral oophorectomy), or with bilateral tubal ligation or Essure® (hysteroscopic bilateral tubal occlusion) with confirmation of occlusion of the fallopian tubes performed at least 3 months prior to Screening, or postmenopausal (defined as at least 12 months post cessation of menses without an alternative medical cause and follicle-stimulating hormone [FSH] level

  ≥ 40 mIU/mL). Males will agree to use contraception and refrain from sperm donation.

• Body mass index between 30.0 and 39.9 kg/m^2, inclusive, at Screening.

• Glycosylated hemoglobin (HbA1c) level of < 6.5% at Screening (test may be repeated once for confirmation of out-of-range values).

• Vital signs at Screening and Check-in as per the following ranges and stable (measured in a supine position after a minimum of 5 minutes of rest):

  1. Systolic blood pressure ≥ 90 and ≤ 140 mmHg
  2. Diastolic blood pressure ≥ 50 and ≤ 90 mmHg
  3. Pulse rate ≥ 50 and ≤ 100 bpm.

• In good health, determined by no clinically significant findings from medical history, physical examination, 12-lead ECG, vital sign measurements, and clinical laboratory evaluations at Screening and/or Check-in as assessed by the Investigator (or designee).

Exclusion Criteria:

• Any clinically important illness, medical/surgical procedure, or trauma within 4 weeks prior to dose administration on Day 1.

• Significant history or clinical manifestation of any metabolic, allergic, dermatological, hepatic, renal, hematological, pulmonary, cardiovascular, gastrointestinal, neurological, respiratory, endocrine, or psychiatric disorder, as determined by the Investigator (or designee).

• Obesity induced by known endocrine or genetic disorders (eg, Cushing syndrome, hypothyroidism, Prader Willi syndrome).

• Any previous surgical treatment or procedures with medical devices (such as insertion of lap band or gastric balloons) for obesity (excluding liposuction if performed > 1 year prior to Check-in).

• History of significant hypersensitivity, intolerance, or allergy to any drug compound, food, or other substance, which would increase the subject's risk of participation.

• History of stomach or intestinal surgery or resection that would potentially alter absorption and/or excretion of orally administered drugs (uncomplicated appendectomy, cholecystectomy, and hernia repair > 6 months prior to Screening will be allowed).

• History or evidence of underlying liver disease, including viral (hepatitis B and C) or alcoholic hepatitis, or confirmed diagnosis of nonalcoholic steatohepatitis (NASH); nonalcoholic fatty liver disease with qualifying liver function tests (LFTs) will be allowed.

• Gilbert's Syndrome (congenital non-hemolytic hyperbilirubinemia) or suspicion of Gilbert's Syndrome based on total and direct bilirubin.

• Laboratory results that exceed the following thresholds at Screening AND Check-in (laboratory tests may be repeated once for confirmation of out-of-range values) as specified:

  1. alanine aminotransferase (ALT) > 1.5 × upper limit of normal (ULN)
  2. aspartate aminotransferase (AST) > 1.5 × ULN
  3. gamma glutamyl transferase (GGT), alkaline phosphatase (ALP), total bilirubin, or International Normalized Ratio (INR) > ULN
  4. Hemoglobinopathy, hemolytic anemia, or chronic anemia (hemoglobin concentration < 13.0 g/dL [130 g/L] for males, < 11.0 g/dL [110 g/L] for females) at Screening or any other condition known to interfere with interpretation of HbA1c measurement
  5. Neutrophils < 1.5 × 109/L deemed clinically significant by Investigator upon a confirmatory repeat
  6. Thyroid-stimulating hormone (TSH) level above the normal range, confirmed on repeat.

• History or presence of cardiac arrhythmia (at the discretion of the Investigator) or congenital long QT syndrome.

• A QT interval corrected for heart rate using Fridericia's method (QTcF) > 450 msec for males or > 470 msec for females on Screening ECG. At the discretion of the Investigator, ECG may be repeated twice and an average taken of the 3 readings.

• The subject has creatinine clearance ≤ 80 mL/minute as calculated using the Cockroft-Gault equation. At the discretion of the Investigator, evaluation may be repeated once to confirm.

• History of alcoholism or drug/chemical abuse within 2 years prior to Check in.

• Alcohol consumption of > 14 units per week. One unit of alcohol equals 12 oz (360 mL) of beer, 1½ oz (45 mL) of liquor, or 5 oz (150 mL) of wine.

• Positive urine drug screen at Screening; or positive alcohol breath test result or positive urine drug screen at Check-in.

• Positive hepatitis B surface antigen and/or hepatitis C antibody and/or positive human immunodeficiency virus 1/2 (Appendix 2).

• Participation in a clinical study involving administration of an investigational drug (new chemical entity) in the past 30 days or 5 half-lives prior to dosing, whichever is longer.

• Subjects who are actively dieting, have gained or lost > 5 pounds, or using or intend to use any prescription or nonprescription drugs for weight loss including herbal or other dietary supplements within 3 months prior to Check-in.

• Use or intend to use any medications/products known to alter drug absorption, metabolism, or elimination processes, including St. John's wort, within 30 days prior to Check-in and throughout the outpatient Follow-up period.

• Use or intend to use any prescription medications/products within 30 days prior to Check-in, unless deemed acceptable by the Investigator (or designee).

• Use or intend to use slow-release medications/products considered to still be active within 14 days prior to Check-in, unless deemed acceptable by the Investigator (or designee).

• Use or intend to use any nonprescription medications/products including vitamins, minerals, and phytotherapeutic/herbal/plant-derived preparations within 14 days prior to Check-in and throughout the outpatient Follow-up period, unless deemed acceptable by the Investigator (or designee).

• Consumption of alcohol from 72 hours prior to Check-in.

• Use of tobacco- or nicotine-containing products (including nicotine and non-nicotine e-cigarettes, vaping, etc.) within 3 months prior to Check-in, or positive cotinine at Screening or Check-in.

• Receipt of blood products within 2 months prior to Check-in.

• Donation of blood from 8 weeks prior to Screening, plasma from 2 weeks prior to Screening, or platelets from 6 weeks prior to Screening.

• Poor peripheral venous access.

• Have previously completed or withdrawn from this study or any other study investigating ERX1000, and have previously received the investigational product.

• Subjects who, in the opinion of the Investigator (or designee), should not participate in this study.