AGN-242428 in the Treatment of Plaque Psoriasis

Inclusion Criteria:

Participants who have a confirmed diagnosis of plaque psoriasis, diagnosed at least 6 months before study with a Physician's Global Assessment (PGA) score ≥ 3 at screening and baseline
Severity of disease must be at least moderate, defined as Psoriasis Area and Severity Index (PASI) ≥ 12 and % body surface area (BSA) ≥ 10
Participant is a candidate for phototherapy or systemic therapy for psoriasis
Body weight of at least 55 kilograms (kg) (121 (pound) lbs)

Exclusion Criteria:

Non-plaque forms of psoriasis (erythrodermic, guttate, pustular) or drug-induced psoriasis
Psoriasis which has not been stable for the 4 weeks prior to screening and which is unstable at Study Day 1
History of Gilbert's, Rotor, or Dubin-Johnson syndromes or any other disorder of bilirubin metabolism
History of active mycobacterium tuberculosis (TB) infection or untreated or inadequately treated latent TB
Positive QuantiFERON test for TB infection at screening
Had a vaccination with Bacillus Calmette-Guérin (BCG) within 12 months prior to baseline
Positive drug and/or alcohol test at screening (with the exception of marijuana). Retesting in the case of a positive alcohol test is allowed at the discretion of the sponsor
Current treatment or history of treatment with any anti-Tumor Necrosis Factor alpha (TNFα) biologic therapy within 3 months or 5 half-lives of study, and/or all other biologics within 6 months of study (Day 1)
Efficacy failure on 2 or more biologic agents for the treatment of psoriasis when the failures occurred within 1 year of the initiation of the therapy of the first biologic agent
Alanine aminotransferase (ALT), aspartate aminotransferase (AST) or total bilirubin (TBL) exceeding 1.5 times the upper limit of normal (ULN) at screening.