This is a phase I, randomized, double-blinded, placebo-controlled, single and multiple dose escalation study to evaluate the safety, tolerability, pharmacokinetic characteristics and pharmacodynamics of HX15001 in adult healthy participants.

The study consists of two parts: Part A involves single-dose escalation (Cohorts 1-7), and Part B involves multiple-dose escalation (Cohorts 8-9).

The primary objective of this study is to characterize the safety and tolerability of single and multiple doses of HX15001 in healthy subjects.

This study consists of two parts. Part A: This part includes seven sequential ascending-dose cohorts, designated as Cohorts 1 through 7. Cohort 1 and Cohort 6 will enroll four healthy subjects in each cohort. Cohort 2 will enroll six healthy subjects. The remaining four cohorts will enroll eight healthy subjects each.

On Day 1, after final eligibility has been determined, subjects in Cohorts 1-5 will be randomly assigned to receive a single subcutaneous dose (which may be split into multiple dosing syringes) of HX15001 or placebo, while subjects in Cohorts 6 and 7 will be randomly assigned to receive a single intravenous infusion of HX15001 or placebo. The doses for Cohorts 1-7 will be administered as per the protocol.

Part B: This part consists of two multiple-dose cohorts (Cohorts 8 and 9), each enrolling eight healthy subjects. Subjects in these cohorts will receive subcutaneous doses of HX15001 or placebo on Days 1, 15, and 43. Dosing will be followed by safety, pharmacokinetic, pharmacodynamic, and immunogenicity assessments.

Study Period Part A: Screening：Up to 28 days Treatment：Day 1 single dose Follow up: 112 days including Day 1 (Cohort 1-3) 140 days including Day 1 (Cohort 4-7) Part B: Screening：Up to 28 days Treatment：Day 1, Day 15, Day 43 (single dose on each visit) Follow up: 20 weeks (Day 183) The final follow-up visit will be determined based on the safety and PK data derived from the previous SAD and MAD cohorts, which may be earlier or later than Day 183 (±7 days

Inclusion Criteria:

1. An informed consent document signed and dated by the subject.
2. Healthy male and female subjects of any ethnic origin between the ages of 18 and 55 years, inclusive.
3. Have a Body mass index (BMI) of 18-32 kg/m2 , inclusive; with body weight ≥50 kg during the screening.
4. In good health, as determined by the investigator at Screening procedures, with no clinically significant findings from medical history, physical examination, 12-lead ECG, vital signs measurements, and clinical laboratory evaluations.
5. Subjects must be willing to understand and comply with all research procedures and restrictions, and able to communicate effectively with researchers.

Exclusion Criteria:

1. Females who are pregnant, planning to become pregnant, or breastfeeding during the trial.
2. Has a positive result of pregnancy test at Screening or Baseline
3. History of HIV infection, hepatitis B, hepatitis C or syphilis; positive testing for HIV, hepatitis B, HCV Ab or serological reaction of syphilis
4. Subjects at risk for tuberculosis (TB).
5. Unwilling or unable to comply with the criteria in the Lifestyle Considerations section of this protocol;
6. Has received an experimental agent (vaccine, drug, biologic, device, blood product or medication) within 30 days or 5 half-lives prior to dosing, or plan to receive another experimental agent during the duration of this trial;
7. Subjects who have donated blood (excluding plasma donations) of approximately 1 pint (500 mL) or more within 30 days prior to dosing, or those who plan to donate blood during the study period or within 30 days after the end of the study;
8. Use of prescription or over-the-counter drugs or dietary or herbal supplements within 7 days or 5 half-lives (whichever is longer) prior to dosing
9. Triplicate 12-lead electrocardiogram (ECG) that demonstrates clinically relevant abnormalities that may affect participant safety or interpretation of study results
10. Has clinically significant interventional therapies (surgery, paracentesis, etc.) within 6 months prior to dosing, or plan to have any surgeries during the duration the trial.
11. History of any hypersensitivity or allergic reaction to drugs;
12. Has any other conditions that would, in the opinion of the investigator, put the subjects at increased risk for participation in this trial