A Study of Ixekizumab (LY2439821) Compared to Guselkumab in Participants With Moderate-to-Severe Plaque Psoriasis

Inclusion Criteria:

- Have chronic plaque psoriasis based on a diagnosis for at least 6 months before
baseline as determined by the investigator.

- Are a candidate for phototherapy and/or systemic therapy.

- Have both an sPGA score of ≥3 and a PASI score ≥12 at screening and at baseline.

- Have ≥10% body surface area (BSA) involvement at screening and baseline.

- If a male, agree to use a reliable method of birth control during the study.

- If female, agree to use highly effective method of contraception.

Exclusion Criteria:

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

- Have a history of drug-induced psoriasis.

- Had a clinically significant flare of psoriasis during the 12 weeks before baseline.

- Use of tanning booths for at least 4 weeks before baseline.

- Concurrent or recent use of any biologic agent within the following periods prior to
baseline: etanercept <28 days; infliximab, adalimumab, certolizumab pegol, or
alefacept <60 days; golimumab <90 days; rituximab <12 months; secukinumab <5 months;
or any other biologic agent (e.g., ustekinumab) <5 half lives.

- Have prior use of IL-23p19 antagonists (e.g., guselkumab, tildrakizumab,
risankizumab), or have any condition or contraindication as addressed in the local
labeling for guselkumab 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- Have previously completed or withdrawn from this study, participated in any other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 or guselkumab, have participated in any study investigating
other IL-17 or IL-23p19 antagonists, or have received treatment with ixekizumab.

- Have previously failed to respond to an IL-17 antagonist, per investigator assessment.

- Have had a live vaccination within 12 weeks of baseline.

- Have a known allergy or hypersensitivity to any biologic therapy.

- Have had any major surgery within 8 weeks of baseline.

- Have had a serious infection, have been hospitalized, or have received intravenous
antibiotics for an infection within 12 weeks of baseline.

- Are women who are pregnant, or who are lactating (breast-feeding).