This study is a first-in-human clinical trial of CMS-D008 conducted in Chinese healthy and overweight or obese adult participants, consisting of three parts: Part-1 Single Ascending Dose (SAD) study (hereinafter referred to as Part-1 SAD study), Part-2 Multiple Ascending Dose (MAD) study (hereinafter referred to as Part-2 MAD study), and Part-3 expansion study. The study aims to evaluate the safety, tolerability, pharmacokinetic (PK), pharmacodynamic (PD) characteristics, and immunogenicity of single and multiple subcutaneous injections of CMS-D008 injection in Chinese healthy and overweight or obese adult participants.

Inclusion Criteria:

1. Voluntarily participate in this study, sign the informed consent form, be able to understand and comply with all requirements and restrictions of the study, and complete the study in accordance with the protocol.
2. Male or female aged 18-56 years (inclusive)
3. Body mass index (BMI) ≥23 kg/m2 at screening, with stable body weight in the past 4 months
4. Glycated hemoglobin (HbA1c) < 6.5% and fasting plasma glucose < 7 mmol/L at screening.
5. Participants of childbearing potential (including their partners) have no plan to conceive, donate oocytes, or donate sperm from the date of signing the informed consent form until 7 months after the last study drug administration, and must comply with contraceptive requirements during this period

Exclusion Criteria:

1. History or presence of liver disease (except fatty liver disease), allergy, cardiovascular, endocrine (except primary obesity), neuropsychiatric, digestive, respiratory, hematological, immune, or genitourinary system major diseases.
2. History or presence of endocrine diseases that may significantly affect body weight, or obesity caused by medication use, single gene mutation, or genetic obesity syndromes.
3. Any skin conditions that may interfere with the assessment of injection-site reactions.
4. Use of any siRNA agent in the prior 12 months
5. Use of glucagon-like peptide-1 (GLP-1) receptor agonists and other weight-loss medications in the past 6 months.
6. Use of any prescription or non-prescription drugs (including Chinese herbal medicines, vitamins, minerals, and dietary supplements, etc.) within 2 weeks before dosing or at least 5 elimination half-lives, whichever is longer.
7. Participants with clinically significant abnormalities in vital signs, physical examination, laboratory tests, 12-lead ECG, and other auxiliary examinations at screening or baseline, who are considered by the investigator to be ineligible for enrollment.