Due to unexpected operational issues outside of Lilly's control the study has been closed

This study will assess the safety and efficacy of ixekizumab (LY2439821) compared to placebo in participants with active AS.

Inclusion Criteria:

• Diagnosis of moderate to severe AS with prior documented radiologic evidence (X-ray) fulfilling the Modified New York criteria for AS (1984)
• Have active AS defined as Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) ≥4 and the spinal pain (back pain) score ≥4 on a numeric rating scale (NRS)
• Participants should have been on nonsteroidal anti-inflammatory drugs (NSAIDs) with an inadequate response
• Participants who are regularly taking NSAIDs or cyclooxygenase-2 (COX-2) inhibitors as part of their AS therapy are required to be on a stable dose
• Participants who have been on a tumor necrosis factor alpha (TNF) inhibitor (not more than one) must have experienced an inadequate response
• Total duration of prior therapy (NSAIDs and/or adequate physical therapy) should be at least 12 weeks
• Men must agree to use a reliable method of birth control or remain abstinent during the study
• Women must agree to use reliable birth control or remain abstinent during the study and for at least 12 weeks after stopping treatment

Exclusion Criteria:

• Participants with a total ankylosis of the spine
• Prior or current treatment with adalimumab
• Participants previously treated with any biological or other immunomodulating agents except for those targeting TNF
• Evidence of active inflammatory arthritic syndromes or spondyloarthropathies other than ankylosing spondylitis
• Have participated in any study with interleukin 17 (IL-17) antagonists, including ixekizumab
• Serious disorder or illness other than ankylosing spondylitis
• Serious infection within the last 3 months
• Breastfeeding or nursing (lactating) women