A Study in Patients With Moderate to Severe Plaque Psoriasis to Evaluate the Efficacy and Safety of ESK-001

Inclusion criteria

• Males or females, age ≥18 years
• Diagnosis of plaque psoriasis for ≥6 months
• Plaques covering ≥10% of BSA
• PASI ≥12
• sPGA ≥3
• Women of childbearing potential (WOCBP) and males who are sexually active with WOCBP must agree to adhere to highly effective methods of contraception

Exclusion criteria

• Nonplaque psoriasis or other inflammatory skin conditions
• Immune-mediated conditions commonly associated with psoriasis (eg inflammatory bowel disease). Patients with psoriatic arthritis may participate
• Pregnant, lactating, or planning to get pregnant during the study
• Use of drugs prior to Study Day 1 that treat or may affect psoriasis:

• Topical within 2 weeks
• Phototherapy or any systemic treatments within 4 weeks
• Any biologic agent targeted to IL-12 or IL-23 within 6 months, oral IL-12 or IL-23 or TNFα inhibitor within 2 months, or IL-17 within 4 months
• Systemic immunosuppressants or immunomodulatory drugs within 4 weeks
• Modulators of B cells within 6 months, or T cells within 3 months
• JAK inhibitors or TYK2 inhibitors within 4 weeks
• PDE4 inhibitor within 2 months
• Any investigational agent, within 30 days or 5 half-lives or is currently enrolled in an investigational study
• Lack of clinical response to a TYK2, IL-12, or IL-23 targeted psoriasis treatment
• Patients with QTcF >450 msec (males) or >470 msec (females) at Screening
• Unstable cardiovascular disease, defined as a recent clinical deterioration or a cardiac hospitalization within the last 3 months
• Evidence of recent or recurrent herpes zoster or herpes simplex viral infection
• Evidence of active infection or positive test result for hepatitis B, hepatitis C, HIV or TB
• History of serious bacterial, fungal, or viral infections that led to hospitalization, or any recent serious infection requiring antibiotic treatment
• Any history of known or suspected congenital or acquired immunodeficiency state or condition that would compromise the patient's immune status
• Lab abnormalities indicating significant renal, hepatic or bone marrow dysfunction
• History of any immune-mediated or inflammatory medical condition for which patient requires current systemic corticosteroids