A Study of Ixekizumab (LY2439821) in Participants With Active Psoriatic Arthritis

Inclusion Criteria:

• Presents with established diagnosis of active psoriatic arthritis (PsA) for at least 6months, and currently meets Classification for Psoriatic Arthritis (CASPAR) criteria

• Active PsA defined as the presence of at least 3 tender and at least 3 swollen joints

• Presence of active psoriatic skin lesion or a history of plaque psoriasis (Ps)

• Men must agree to use a reliable method of birth control or remain abstinent duringthe study

• Women must agree to use reliable birth control or remain abstinent during the studyand for at least 12 weeks after stopping treatment

• Have been treated with 1 or more conventional disease-modifying antirheumatic drugs (cDMARDs)

• Have had prior treatment with at least 1 and not more than 2 tumor necrosis factor (TNF) inhibitors. The participant must have discontinued at least 1 TNF inhibitor dueto either an inadequate response (based on a minimum of 12 weeks on therapy) ordocumented intolerance.

Exclusion Criteria:

• Current use of biologic agents for treatment of Ps or PsA

• Inadequate response to greater than 2 biologic DMARDs

• Current use of more than one cDMARDs

• Diagnosis of active inflammatory arthritic syndromes or spondyloarthropathies otherthan PsA

• Have received treatment with interleukin (IL) -17 or IL12/23 targeted monoclonalantibody (MAb) therapy

• Serious disorder or illness other than psoriatic arthritis

• Serious infection within the last 3 months

• Breastfeeding or nursing (lactating) women