This is a randomized, double-blind, placebo-controlled study. Approximately 120 patients who meet the eligibility criteria will be randomized to one of three treatment cohorts (JS005 150 mg, 300 mg, 450mg in a ratio of 1:1:1),then using secondary randomization method, 40 patients in each group will be randomized in a 3: 1 ratio to receive investigational product or placebo.~JS005 150mg Cohort: JS005 150 mg or placebo treatment(JS005:Placrbo=3:1) s.c. prefilled syringe (PFS) on Week 0, 1, 2, 3, 4,8 and 12~JS005 300mg Cohort: JS005 300 mg or placebo treatment(JS005:Placrbo=3:1) s.c. PFS on Week0, 1, 2 ,3, 4,8,and 12 3 .JS005 450mg Cohort: JS005 450 mg or placebo treatment(JS005:Placrbo=3:1) s.c. PFS on Week0, 1, 2 ,3, 4,8,and 12 Based on the clinical judgment of disease activity by the investigator and the patient, background medications, such as NSAIDs and DMARDs, may have been modified or added to treat signs and symptoms of nr-axSpA from Week 16 on.
The purpose of this study is to evaluate preliminary efficacy, safety pharmacokinetic (PK) characteristics, pharmacodynamics (PD) haracteristics and immunogenicity of JS005 at different doses in Chinese patients with active non-radiographic axial spondyloarthritis(nr-axSpA). Treatment difference of JS005 150mg,300mg,450mg vs. placebo in Chinese nr-axSpA patients in terms of ASAS 40 response rate at Week 16 as well as safety profile will be provided by the study .