['plaque psoriasis']
['ixekizumab', 'ustekinumab', 'placebo']

        Inclusion Criteria:

          -  Chronic plaque psoriasis for at least 6 months before baseline

          -  Failure, contraindication, or intolerability to at least 1 systemic therapy (including
             cyclosporine, methotrexate, or phototherapy)

          -  Psoriasis Area Severity Index (PASI) score at least 10 at screening and at baseline

          -  Participant must agree to use reliable method of birth control during the study; women
             must continue using birth control for at least 15 weeks after stopping treatment

        Exclusion Criteria:

          -  Predominant pattern of pustular, erythrodermic, and/or guttate forms of psoriasis

          -  History of drug-induced psoriasis

          -  Cannot avoid excessive sun exposure or use of tanning booths for at least 4 weeks
             before baseline and during the study

          -  Have received systemic nonbiologic psoriasis therapy or phototherapy within 4 weeks of
             baseline, or have had topical psoriasis treatment within the 2 weeks of baseline

          -  Concurrent or recent use of any biologic agent within the following washout periods:
             etanercept <28 days; infliximab, adalimumab, or alefacept <60 days; golimumab <90
             days; rituximab <12 months; or any other biologic agent <5 half-lives prior to
             baseline

          -  Have prior use of ustekinumab, or have any condition or contraindication to
             ustekinumab that would preclude the participant from participating in this protocol

          -  Have previously completed or withdrawn from this study, participated in any other
             study with ixekizumab, have participated in any study investigating other interleukin
             (IL)-17 or IL-12/23 antagonists, or have received treatment with other IL-17 or
             IL-12/23 antagonists

          -  Have had a live vaccination within 12 weeks of baseline, or intend to have a live
             vaccination during the course of the study or within 15 weeks of completing treatment
             in this study

          -  Have had a vaccination with Bacillus Calmette-Guérin (BCG) within 12 months of
             baseline or intend to have vaccination with BCG during the course of the study or
             within 12 months of completing treatment in this study

          -  Have a known allergy or hypersensitivity to latex

          -  Have had any major surgery within 8 weeks of baseline or will require such during the
             study

          -  Have active or history of malignant disease within 5 years prior to baseline

          -  Significant uncontrolled disorder

          -  Ongoing infection or serious infection within 12 weeks of baseline; serious bone or
             joint infection within 24 weeks of baseline

          -  Are women who are lactating or breast-feeding
      