XKH001 Injection in Healthy Subjects

A total of 5 cohorts are planned, with 8 subjects (6 on XKH001 and 2 on placebo) in each cohort. The dosing schedule for the first 3 cohorts is as follows: Cohort Dosing Regimen 1. 100 mg Q4W (D1, D29, D57) 2. 300 mg Q4W (D1, D29, D57) 3. 600 mg Q4W (D1, D29, D57) After completion of a 6-week safety observation (D1\~D43) in the previous cohort, the safety data will be reviewed (blinded) by the investigator and the Sponsor to assess the safety and tolerability of the investigational product. If the dose regimen for the previous cohort is confirmed to be safe and tolerable, dose escalation will continue to the next cohort. The Sponsor will discuss with the investigator to decide whether to conduct the 4th to 5th cohorts (e.g., 600 mg Q14D, and the specific dose regimen will be determined at that time) no later than the completion of the safety assessment for Cohort 3. Healthy subjects will be screened within 7 days prior to the first dose and successfully screened subjects will be assigned to the currently ongoing cohort and randomized to receive XKH001 or placebo. Subjects will be admitted to the study site the day before each scheduled dose (D-1, or D28, or D56), complete necessary pre-dose safety assessments, receive SC injection of XKH001 or placebo on D1, or D29, or D57, respectively, and continue to undergo regular safety assessment procedures and other blood sampling (PK, PD, and ADA) after dosing. Subjects will also undergo comprehensive safety assessments on D15, D43, D71, D85, D113, D141 and D169, including AEs/serious adverse events (SAEs), vital signs, physical examinations, laboratory tests (hematology, blood chemistry, coagulation, urinalysis), 12-lead ECG, etc. Safety data as of D43 will be used by the Sponsor and investigator to assess the safety and tolerability of the investigational product. If a subject discontinues treatment prematurely, the "Early Withdrawal" visit and all procedures will be performed as on D169.