Single subcutaneous dose of SHR-1894 in healthy adults

Inclusion Criteria:

1. The subject has voluntarily provided written informed consent, fully understands the purpose and significance of this trial, and is willing to comply with the study protocol.
2. Healthy male or female subjects, aged 18 to 45 years (inclusive) at the time of signing the informed consent form.
3. Body weight ≥ 50 kg for males and ≥ 45 kg for females. Body mass index (BMI) = weight (kg)/height\^2 (m²). BMI between 19 and 26 kg/m², inclusive.
4. Subjects with no abnormalities, or only minor abnormalities deemed clinically insignificant by the investigator, in physical examination, vital signs, 12-lead electrocardiogram (ECG), posteroanterior and lateral chest radiographs, abdominal ultrasound, and laboratory tests during the screening and baseline periods.
5. Female subjects of childbearing potential and male subjects with partners of childbearing age must have been using highly effective contraception for at least 2 weeks prior to signing the informed consent form. They must be willing to either abstain from sexual intercourse or agree to continue using highly effective contraception from the time of signing the informed consent until the end of the follow-up period, and must have no plans for conception or donation of sperm/ova.

Exclusion Criteria:

1. Subjects with a history or current diagnosis of any clinically significant disease, as determined by the investigator, involving the urinary, circulatory, endocrine, neurological, digestive, respiratory, hematopoietic, immune systems, or psychiatric and metabolic disorders.
2. Subjects who, in the investigator's judgment, have any condition or disease that may affect the absorption, metabolism, and/or excretion of the investigational drug.
3. Subjects who have experienced severe infection, severe trauma, or undergone major surgery within 1 month prior to the screening period; or who plan to undergo surgery during the trial period.
4. Subjects with a known allergy to the investigational drug or any of its components, or with a history of atopy (e.g., asthma, eczema).
5. Subjects will be excluded if they meet any of the following criteria: Use of any medication (including prescription drugs, over-the-counter medications, Chinese herbal medicines, dietary supplements, and vitamin A and its derivatives, with the exception of other routine vitamins and occasional use of acetaminophen) within 2 weeks prior to screening.Any medication taken within 5 half-lives prior to screening (whichever period is longer).Planned use of any non-study medication during the trial period.
6. Subjects will be excluded for any of the following: Participation in any other drug or medical device clinical trial within 3 months prior to screening or planned participation during the study period.Any prior investigational drug taken within 5 half-lives prior to screening (whichever washout period is longer).
7. Female subjects who are pregnant, breastfeeding, or have a positive pregnancy test result at screening or baseline.
8. Subjects with a history of blood donation (≥ 400 mL) or significant blood loss within 8 weeks prior to screening, or who received a blood transfusion within 4 weeks prior to screening or baseline; or who intend to donate blood during the trial period.
9. Subjects who have received any vaccination within 2 weeks prior to screening or who plan to receive any vaccination during the trial.
10. Subjects with a history of significant smoking (averaging \>5 cigarettes per day) within 4 weeks prior to screening, or who are unable to abstain from using any tobacco products during the trial period.
11. Subjects meeting any of the following criteria will be excluded: Average daily alcohol intake exceeding 15 g (equivalent to 450 mL of beer, 150 mL of wine, or approximately 50 mL of low-alcohol spirits) within 4 weeks prior to screening.Inability to abstain from alcohol consumption during the trial period.A positive alcohol breath test at baseline.
12. Subjects with a history of illicit drug use or substance abuse/dependence prior to screening; or a positive urine drug test at baseline.
13. Subjects with special dietary requirements that prevent compliance with the standardized diet.
14. Subjects with difficult venous access or whose physical condition cannot tolerate frequent blood sampling.