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.