Inclusion Criteria:
1. Male or female, aged between 18 and 55 years (inclusive) at the time of signing the informed consent form (ICF).
2. Body weight ≥ 50 kg for males and ≥ 45 kg for females at screening, and body mass index (BMI) between 18 and 30 kg/m2 (inclusive).
3. No clinically significant abnormalities in medical history, physical examination, vital signs, laboratory tests (hematology, urinalysis, blood chemistry, coagulation function, etc.), electrocardiogram (ECG), and pulmonary imaging tests, or values outside the normal reference range considered not clinically significant by the investigator during the screening period or before randomization.
4. Men and women of childbearing potential (WOCBP) must agree to use highly effective contraceptive measures from the screening period to 3 months after the end of the study, and not plan to father a child (for men) or become pregnant (for women) from signing the ICF to 3 months after the end of the study. WOCBP must have a pregnancy test result within the normal range at screening or before randomization, and must not be breastfeeding. Women not of childbearing potential are those who are permanently sterilized (e.g., hysterectomy) or postmenopausal.
5. Able to understand the study procedures, voluntarily participate in the study, provide written informed consent, comply with all study requirements, and complete the study.
Exclusion Criteria:
1. Known allergy to any component of the GenSci164 injection formulation, or a history of severe allergic reactions to any drugs, compounds, foods, or other substances, or a history of allergic diathesis.
2. The proposed injection site has tattoos, sunburn, scarring, or other factors that might interfere with the evaluation of the injection site.
3. History or presence of serious metabolic, allergic, dermatological, hepatic, renal, hematological, cardiovascular, gastrointestinal, psychiatric, neurological, respiratory, and/or other significant medical conditions that, in the investigator's opinion, may affect the evaluation of this study.
4. Known confirmed history of malignancy.
5. Participants with a history of epileptic seizures or an increased risk of epileptic seizures, or participants with a recent history (within 6 months prior to screening) of head trauma resulting in loss of consciousness or concussion.
6. History of psychiatric or neurological disorders, or limited ability to perform normal activities, or cognitive impairment.
7. Severe trauma or major surgery within 12 months prior to screening, or gastrointestinal diseases within 3 months prior to screening that could affect the absorption, distribution, metabolism, excretion, or safety evaluation of the IMP.
8. Clinically significant abnormal vital signs at screening (and remaining abnormal and clinically significant upon repeat measurement as determined by the investigator), including, but not limited to, systolic blood pressure ≥ 140 mmHg or \< 90 mmHg, or diastolic blood pressure ≥ 90 mmHg or \< 50 mmHg.
9. Positive hepatitis B surface antigen (HBsAg), positive hepatitis C virus antibody (HCV-Ab), preliminary positive human immunodeficiency virus antigen/antibody (HIV Ag/Ab) test, or positive Treponema pallidum antibody (TP-Ab) at screening.
10. Clinically significant abnormal findings on chest X-ray.
11. As judged by the investigator, participants who are currently using any medications (including over-the-counter \[OTC\] drugs, herbal, or homeopathic preparations) that cannot be discontinued or avoided from 4 weeks prior to randomization (or the time period defined below) through 1 month after randomization.
12. For female participants, use of hormone replacement therapy within 3 months prior to randomization.
13. Participation in any clinical trial of an investigational drug (including investigational vaccines) and receipt of the investigational drug within 3 months or within 5 terminal elimination half-lives (whichever is longer) prior to screening; participation in any clinical trial of a medical device within 3 months prior to screening (excluding screening failures); currently participating in other clinical trials.
14. Average weekly alcohol consumption exceeding the limit within 6 months prior to randomization \[defined as an average weekly intake of \> 14 units, where 1 unit of alcohol = 150 mL of wine, or 360 mL of beer, or 45 mL of spirits\].
15. Average daily smoking of ≥ 5 cigarettes within 6 months prior to randomization, and/or unwillingness to quit smoking during the study, and/or positive nicotine test.
16. Positive alcohol breath test, or history of drug abuse, or use of soft drugs (e.g., marijuana) within 3 months prior to screening, or use of hard drugs (e.g., cocaine and ketamine) within 1 year prior to screening, or positive drug screening result \[including but not limited to morphine, ketamine, 3,4-methylenedioxyamphetamine, methamphetamine, tetrahydrocannabinol (THC), cocaine\].
17. Blood donation or blood loss of ≥ 400 mL, or receipt of blood products within 3 months prior to randomization; poor peripheral venous access, or inability to tolerate blood collection due to physical condition.
18. Study staff, site personnel, or other persons directly involved in the execution of the protocol.
19. Any other medical condition that, in the investigator's opinion, would impair the participant's ability to tolerate the IMP or to continue with the procedures required by this study.
