A Multicenter, Randomized, Double-blind, Double Dummy，placebo and Positive Controlled，phase II Clinical Study to Evaluate the Efficacy and Safety of 608 in Patients with Ankylosing Spondylitis (AS)

The Percentage of Participants Who Achieved an Assessment of Spondylo Arthritis International Society (ASAS) 20 Response.

时间窗: Week 16.

Assessment of Spondylo Arthritis International Society criteria (ASAS) consist of 6 domains (4 main and 2 additional assessment domains): 1. Patient's global assessment measured on a NRS; 2. Patient's assessment of back pain, measured on a NRS; 3. Function represented by Bath Ankylosing Spondylitis Functional Index (BASFI) average of 10 questions as measured by NRS; 4. Inflammation represented by mean duration and severity of morning stiffness, on the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) as measured by NRS; 5. Spinal mobility represented by the Bath Ankylosing Spondylitis Metrology Index (BASMI) lateral spinal flexion assessment; 6. C-reactive protein (acute phase reactant). ASAS 20 response is defined as an improvement of ≥20% and ≥1 unit on a scale of 10 in at least three of the four main domains and no worsening of ≥20% and ≥1 unit on a scale of 10 in the remaining domain. A higher score on the NRS signifies higher severity.