To Evaluate the Safety and Tolerability, Pharmacokinetics and Biomarker of GenSci161 in a Randomized, Double-blind, Placebo-controlled Study in Healthy Adult Participants.

Inclusion Criteria:

1. Healthy adult male or female participants, aged 18 to 45 years (inclusive) at the time of signing the informed consent form (ICF).
2. Male body weight ≥ 50 kg and female body weight ≥ 45 kg at screening; body mass index (BMI) between 18 and 28 kg/m² (inclusive).
3. In good general condition as determined by medical history, screening period assessments, such as physical examination, vital signs, ECG, laboratory tests, and imaging examinations, with all results within reference ranges or deemed clinically insignificant by the investigator.
4. Male and female participants of childbearing potential must agree to use highly effective contraception from screening until 6 months after the last dose. From the time of signing the ICF until 6 months after the last dose, they must have no plans for conception, sperm donation, egg donation, or egg cryopreservation. Female participants must have had no unprotected sexual intercourse within 14 days prior to the first dose.
5. Participants must voluntarily sign the ICF, be able to understand and comply with the requirements of this trial protocol, and complete scheduled follow-up visits in a timely manner.

Exclusion Criteria:

1. History of hypersensitivity to GenSci161, any of its excipients, or similar compounds; or a history of allergic diathesis; or a history of allergic diseases.
2. Severe trauma or major surgical procedure (e.g., coronary artery bypass grafting, organ resection, gynecological surgery) within 12 months prior to screening, or planning to undergo any surgery (including cosmetic procedures) during the trial period.
3. Presence of significant active systemic or local infection (including, but not limited to, bacterial, viral, fungal, or parasitic [helminth] infections) at any time from 4 weeks prior to screening until the day of randomization.
4. Intolerance to abdominal subcutaneous injection, or the presence of tattoos, sunburn, scars, or any other factors at the intended injection site that may interfere with site assessment.
5. History or current presence of any clinically significant, poorly controlled chronic disease or organ dysfunction that, in the investigator's judgment, could compromise the trial's conduct. This includes, but is not limited to, disorders of the following systems: neuropsychiatric, cardiovascular, urological, gastrointestinal, respiratory, musculoskeletal, metabolic, endocrine, hematologic, immunologic, and dermatologic, as well as any other major medical conditions and malignancies (with the exception of adequately treated or resected, and resolved non-metastatic basal cell carcinoma or squamous cell carcinoma of the skin).
6. A positive result at screening for hepatitis C virus antibody (HCV-Ab), human immunodeficiency virus antibody (HIV-Ab), treponema pallidum particle agglutination assay (TPPA), or hepatitis B virus (HBV) infection (defined as a positive hepatitis B surface antigen [HBsAg] and/or a positive hepatitis B core antibody [HBcAb] result).
7. Administration of any live or live-attenuated vaccine within 12 weeks prior to screening or planning to receive any live or live-attenuated vaccine (with the exception of inactivated influenza vaccine) during the trial period.
8. Any other condition that, in the judgment of the investigator, would make the participant unsuitable for participation in this clinical trial.