A Study to Determine the Efficacy of ZPL-3893787 in Subjects With Plaque Psoriasis

Inclusion Criteria:

• A documented history of moderate to severe plaque psoriasis for at least 6 months prior to screening.
• Male or female, aged ≥18 years.
• Psoriasis Area and Severity Index (PASI) ≥10 at both Screening and Day 0.
• An Investigator's Global Assessment (IGA) score ≥ 3 at both Screening and Day 0.
• Psoriasis affecting ≥10% BSA at Screening and Day 0.

Exclusion Criteria:

• Current diagnosis of Pustular, Guttate, Erythrodermic, exfoliative or only nail psoriasis or a diagnosis of inverse psoriasis without having plaque psoriasis.
• Concurrent skin disease (e.g. acne) of such severity in the study area that it could interfere with the study evaluation or presence of skin comorbidities that may interfere with study assessments.
• Active skin infections (e.g. impetigo, abscesses) or any other clinically apparent infections.
• Biologic treatments for psoriasis (e.g. Enbrel, Humira, Stelara, Cosentyx) within 3 months of the start of the Run-In.
• Phototherapy (e.g. UVA, UVB, PUVA) within 4 weeks of the start of the Run-In.
• Oral calcineurin inhibitors and immunosuppressants (e.g. cyclosporine, azathioprine, methotrexate) within 4 weeks of the start of the Run-In.
• Systemic corticosteroids within 4 weeks of the start of the Run-In.
• Oral antihistamines and leukotriene inhibitors and tricyclic antidepressants within 1 week of the start of the Run-In.
• Topical steroids (any potency), topical calcineurin inhibitors (tacrolimus, pimecrolimus), salicylic acid and urea containing treatments and coaltar preparations, topical and oral retinoids and vitamin D derivatives, within 1 week of the start of the Run-In.