Evaluate the Preliminary Efficacy, Safety, and PK of Subcutaneous JS005 in Chinese Adult Patients With Active Nr-axSpA

Inclusion Criteria:

1. Patients who do not meet the modified New York criteria for AS in 1984; Meet the 2009axSpA classification criteria recommended by International Assessment Society of AxialSpondyloarthritis (ASAS): inflammatory back pain for at least 3 months; Age of onset < 45 years; Sacroiliitis on MRI with≥ 1 axial spondyloarthritis features or HLA-B27positive with ≥ 2 SpA features (MRI and X-ray of sacroiliac joint as confirmed bycentral readers).
2. Objective signs of inflammation at screening: active inflammation of the sacroiliacjoints on MRI and/or high sensitivity C-reactive protein (hsCRP) > upper limit ofnormal without other diagnoses to explain the MRI results or elevated hsCRP.
3. Active axSpA at screening and baseline: assessed by total Bath ankylosing spondylitisdisease activity index (BASDAI) ≥ 4 (0-10 scale) and spinal pain ≥ 4 (according to the 0-10 NRS scale, BASDAI question #2).
4. Voluntarily participate in this clinical trial and sign the informed consent form.
5. Male or female aged between 18 and 65 years (both inclusive) at the time of signinginformed consent. Female subjects of childbearing age are required to have a confirmednegative result of urine and/or serum pregnancy test performed within 3 days beforerandomization and agree to use reliable contraceptive measures during the study; Malesubjects and their female partners of childbearing age must agree to use reliablecontraception during the study.
6. Patients meet at least one of the following: 1) have an inadequate or ineffectiveresponse to NSAIDs, 2) have been intolerant to at least one dose of NSAIDs, 3) havecontraindications to NSAIDs therapy. Inadequate or ineffective response to NSAIDs isdefined as no remission after continuous treatment with standard doses of at least 2NSAIDs for a total of no less than 4 weeks and no less than 2 weeks for each NSAID.
7. Patients regularly taking NSAIDs as part of their AS therapy are required to maintaina stable dose for at least 2 weeks prior to randomization.
8. Patients using tumor necrosis factor α (TNFα) inhibitors must have experienced aninadequate response to the standard treatment dose for at least 3 months, or have beenintolerant to TNFα inhibitors.

Exclusion Criteria:

1. Unable or unwilling to undergo MRI.
2. Previous exposure to JS005 or any other biologic drug directly targeting IL-17 orIL-17 receptor.
3. Have taken high potency analgesics (e.g., opiates of methadone, hydromorphone,morphine) within 2 weeks prior to randomization.
4. Previous treatment with any intra-articular injection (e.g., glucocorticoids) within 4weeks prior to randomization.
5. Previous treatment with any biological immunomodulating agents other than the TNFαinhibitors.
6. Treatment with JAK inhibitor agents within 8 weeks prior to randomization andunwilling to discontinue during the study.