The main purpose of this study is to evaluate the safety, Tolerability and Pharmacokinetics (PK) of SHR1314 with axial spondyloarthritis.

This was a phase I, multicenter, double-blind, randomized, placebo-controlled study. The study originally planned to enroll 5 cohorts of 8 subjects each (N=40).

Inclusion Criteria:

1. Diagnosis of axial spondyloarthritis (axSpA) and fulfilling the 2009 ASAS classification criteria.
2. Have a history of back pain ≥3 months with age at onset <45 years.
3. Have active axSpA defined as BASDAI ≥4 at screening and baseline.
4. Have objective signs of inflammation by presence of elevated ESR and/or presence of elevated CRP.
5. In the past had an inadequate response to at least 1 or 2 non-steroidal anti-inflammatory drugs (NSAIDS) for duration of 4 weeks or cannot tolerate NSAIDS.
6. If taking NSAIDS be on stable dose for at least 2 weeks prior to randomization.

Exclusion Criteria:

1. History of ongoing, chronic or recurrent infectious disease or evidence of tuberculosis infection.
2. Previous exposure to other biologic drug directly targeting Interleukin (IL)-17 or Interleukin (IL)-17 receptor.
3. Total ankylosis of the spine.
4. Have recently received biologics, tumor necrosis factor inhibitors or other immunomodulatory agents within 12 weeks.
5. Have either a current diagnosis or a recent history of malignant disease.
6. Are pregnant or breastfeeding.