A Single and Multiple Ascending Dose Study of HM17321 in Healthy and Obese Participants

Inclusion Criteria:

* Adults aged 18-65 years.
* Part A: Healthy participants with BMI ≥20 kg/m² and ≤27 kg/m² at screening.
* Part B: Healthy obese participants with BMI ≥30 kg/m² and ≤45 kg/m² at screening.
* Stable body weight (\<5% change) in the past 3 months.
* Able and willing to provide written informed consent.
* Male participants must use contraception or remain abstinent from women of childbearing potential.
* Female participants must not be pregnant or breastfeeding and use highly effective contraception if of childbearing potential.

Exclusion Criteria:

* History of any bariatric procedure.
* Uncontrolled thyroid disease (TSH \>6.0 or \<0.4 mIU/L).
* Abnormal liver function or clinically significant liver disease

  * Part A: ALT or AST ≥ ULN, or total bilirubin ≥ ULN
  * Part B: ALT or AST \>2× ULN, or total bilirubin \>1.5× ULN
* Abnormal pancreatic function

  * Part A: amylase or lipase ≥ ULN
  * Part B: amylase or lipase \>3× ULN
* Clinically significant cardiovascular disorders (e.g., myocardial infarction, congestive heart failure, long QT syndrome).
* Abnormal renal function (eGFR \<60 mL/min/1.73 m²).
* Positive test for hepatitis B, hepatitis C, or HIV at screening.
* Women who are pregnant, planning to become pregnant, or breastfeeding.
* History of drug or alcohol abuse within defined timeframes (e.g., alcohol \>14 standard units/week in past year, or positive drug screen).
* Use of any investigational product within 30 days or 5 half-lives (whichever is longer) prior to screening.
* Additional Exclusion Criteria for Part B

  * HbA1c ≥6.5% or a history of diabetes mellitus (type 1 or type 2).
  * Obesity induced by other endocrine disorders (e.g., Cushing syndrome).
  * Use of weight control treatments (e.g., GLP-1 receptor agonists or other anti-obesity medications) and antihypertensive medications within 3 months prior to screening.
  * Use of any lipid-lowering medications, unless on a stable dose for at least 3 months prior to screening.