Study to evaluate the safety, tolerability, pharmacokinetics and pharmacodynamic effect of JTE-451 administered for 4 weeks in subjects with active plaque psoriasis.

Inclusion Criteria:

• Minimum of two psoriatic plaques (i.e., one clinical target lesion and one biopsy target lesion).
• Each of the two target lesions must have a psoriatic lesion severity sum (PLSS) of ≥6
• Body mass index (BMI) of 18 to 38 kg/m2 (inclusive)

Exclusion Criteria:

• Prior exposure to >2 systemic biologic agents and/or small molecules including investigational therapies for the treatment of psoriasis or have not discontinued systemic biologic agents and/or small molecules anti-psoriasis therapy including investigational therapies due to lack of efficacy;
• Subjects with significant health problems, other than having plaque psoriasis (as determined by medical history, physical examination, chest X-ray, vital signs and 12-lead ECG) that could either interfere with study evaluations or place subject at undue risk;
• Presence of erythrodermic psoriasis, pustular psoriasis, guttate psoriasis, medication-induced psoriasis at Visit 1;
• Conditions (e.g., clinically-significant eczema or severe acne in the target lesion area) that would interfere with study evaluations;
• Positive quantiFERON®-TB Gold test, negative chest X-ray findings for tubercle bacillus (TB) or lack any other evidence of active or latent TB;
• History of a clinically-significant infection (e.g., required oral antimicrobial therapy) within 4 weeks prior to Visit 2;
• Subjects who do not have clinical laboratory test results within the normal reference ranges (i.e., are deemed not to be clinically significant) or clinically not acceptable to the Investigator;