Phase 3 Study of MWN109 Injection in Participants With Overweight or Obesity

Inclusion Criteria: 1. Male or female aged 18 to 65 years (inclusive) at the time of signing the informed consent form; 2. Body weight ≥ 70 kg (males) or ≥ 60 kg (females), with BMI ≥ 28 kg/m² (obesity), or 24 kg/m² ≤ BMI \< 28 kg/m² (overweight) with at least one weight-related comorbidity (e.g., hypertension, dyslipidemia, pre-diabetes, obstructive sleep apnea syndrome, metabolic dysfunction-associated steatotic liver disease, weight-bearing joint pain, cardiovascular disease, polycystic ovary syndrome); 3. Resting heart rate ≥ 55 bpm and ≤ 100 bpm (during screening and prior to randomization per 12-lead ECG); 4. Self-reported or documented history of dietary and exercise-based weight management for at least 12 weeks prior to screening, with \< 5.0% weight change during the 12 weeks prior to screening, and ability to maintain the required diet and exercise behavior during the study; 5. Participants of childbearing potential must agree to use highly effective contraception from 14 days before signing the ICF until 4 months after the last dose, with no plans for pregnancy or oocyte donation; male participants must agree to use highly effective contraception from signing the ICF until 4 months after the last dose, with no plans for fathering children or sperm donation. Exclusion Criteria: 1. Known allergic constitution (allergy to 3 or more foods or drugs), or allergy to GLP-1 receptor agonists or any component of the investigational product, or severe allergic diseases at screening, or history of severe drug allergy. 2. Use of any anti-hyperglycemic agents, weight-affecting medications, or prescription weight-loss medications for weight control within 12 weeks prior to screening; over-the-counter weight-loss medications or appetite suppressants within 4 weeks. 3. Laboratory abnormalities: ALT or AST ≥ 3×ULN; total bilirubin ≥ 1.5×ULN; eGFR \< 60 mL/min/1.73m²; hemoglobin \< 110 g/L (males) or \< 100 g/L (females); serum calcitonin ≥ 35 ng/L; TSH \> 6.0 or \< 0.4 mIU/L; fasting triglycerides ≥ 5.64 mmol/L; serum amylase or lipase \> 2.0×ULN. 4. Known or screening-detected ECG abnormalities with significant safety risk, including: uncontrolled arrhythmias, second-degree or third-degree AV block, ST-T changes suggesting myocardial ischemia, QTcF \> 450 ms, family history of long QT or Brugada syndrome. 5. Has a medical history or evidence of any of the following conditions: secondary or drug-induced overweight or obesity; diagnosis of type 1 or type 2 diabetes mellitus in the past or at screening, or at least one laboratory finding suggestive of diabetes identified at screening: HbA1c ≥ 6.5%, fasting plasma glucose ≥ 7.0 mmol/L, random plasma glucose ≥ 11.1 mmol/L, or 2-hour plasma glucose during the oral glucose tolerance test (OGTT) ≥ 11.1 mmol/L; acute or chronic pancreatitis; gallstones/cholecystitis (with exceptions); thyroid C-cell carcinoma or MEN 2A/2B; prior bariatric surgery (with exceptions); moderate or severe depression (PHQ-9 ≥ 15), other severe psychiatric disorders, or suicidal risk; malignancy within 5 years (with exceptions); cardiac disease within 6 months; premature beats or tachycardia; cerebrovascular event within 6 months; uncontrolled hypertension; thyroid dysfunction; gastric emptying abnormalities; organ transplant history; autoimmune disease; previous or planned weight-loss treatment. 6. Pregnant or breastfeeding women. 7. Previous treatment with MWN109 injection.