A Phase 2b Study of Baricitinib in Participants With Moderate to Severe Psoriasis

Inclusion Criteria:

* You must have active chronic plaque psoriasis for at least 6 months prior to entry into the study
* You are a candidate for systemic therapy and/or phototherapy
* You must have active plaque psoriasis covering at least 12% body surface area
* You must have Psoriasis Area and Severity Index (PASI) score of at least 12
* You must have Static Physician's Global Assessment (sPGA) score of at least 3

Exclusion Criteria:

* You must not have received a biologic agent/monoclonal antibody within 8 weeks prior to entry into the study
* You must not have prior treatment with an oral Janus kinase (JAK) inhibitor
* You must not have received a systemic psoriasis (Ps) therapy within 4 weeks prior to entry into the study
* You must not have received a phototherapy within 4 weeks prior to entry into the study
* You must not have received a topical Ps therapy with psoralens within 4 weeks prior to entry into the study
* You must not be pregnant or nursing
* If female of childbearing potential or a male, and do not agree to use 2 forms of highly effective methods of birth control for at least 28 days following the last dose of investigational product
* You must not have had symptomatic herpes zoster or herpes simplex infection within 12 weeks or have a history of disseminated/complicated herpes zoster
* You must not have evidence of active infection, such as fever ≥38.0ºC (100.4ºF)
* You must not have a history of active hepatitis B, hepatitis C, or human immunodeficiency virus (HIV)
* You must not be immunocompromised and, in the opinion of the investigator, are at an unacceptable risk for participating in the study
* You must not have known history hypogammaglobulinemia
* You must not have had a serious systemic or local infection within 12 weeks prior to entry into the study
* You must not have been exposed to a live vaccine within 12 weeks prior to entry into the study, or expected to need/receive a live vaccine (including herpes zoster vaccination) during the course of the study
* You must not have had household contact with a person with active tuberculosis (TB) and did not receive appropriate and documented prophylaxis for TB
* You must not have a serious and/or unstable illness that, in the opinion of the investigator, poses an unacceptable risk for the your participation in the study
* You must not have or have had a history of lymphoproliferative disease; or signs or symptoms suggestive of possible lymphoproliferative disease, including lymphadenopathy or splenomegaly; or active primary or recurrent malignant disease; or been in remission from clinically significant malignancy for less than 5 years
* You must not have a history of chronic alcohol abuse or intravenous (IV) drug abuse within the last 2 years
* You must not have donated blood of more than 500 mL within 4 weeks
* You must not have received a topical Ps treatment within 2 weeks prior to entry into the study

  * Exceptions:
  * class 6 (mild, such as desonide) or class 7 (least potent, such as hydrocortisone) topical steroids used on the face, axilla, palms, soles, and/or genitalia
  * non-medicated shampoos (for example, that do not contain corticosteroids, coal tar, or vitamin D3 analogues)
  * emollients that do not contain alpha or beta hydroxyl acids