A Study to Evaluate 608 in Patients with Ankylosing Spondylitis (AS)

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)

This study will evaluate the effect and safety of 608 in patients with AS.

The purpose of this study is to demonstrate the clinical efficacy, safety and tolerability of 608 compared to placebo and positive drug in patients with AS.

Inclusion Criteria:

1. Female and male patients at least 18 years of age at the time of screening.
2. Participant with a clinical diagnosis of ankylosing spondylitis (AS) and meeting the modified New York criteria for AS.
3. Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score >= 4 and a Patient's Assessment of Total Back Pain score >= 4 based on a 0 - 10 numeric rating scale (NRS) at the Screening and Baseline visits.
4. If entering the study on concomitant NSAIDs for AS, participant must be on stable dose(s) for at least 2 weeks prior to the Baseline visit.

Exclusion Criteria:

1. Patients with other uncontrolled active inflammatory diseases.
2. Clinical laboratory tests and other tests that reveal abnormalities with clinical significance
3. Patients who have active Hepatitis B, Hepatitis C or HIV infections as determined by positive results at Screening.
4. History of cancer.
5. Known or suspected history of immunosuppression.