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.