This is a randomized, placebo-controlled, ascending single dose study of KHK4827 to evaluate safety, tolerability, pharmacokinetics and pharmacodynamics of subcutaneous or intravenous administration of KHK4827 in healthy male subjects or moderate to severe psoriasis patients.

Inclusion Criteria:

Health volunteers

• Able to provide written informed consent
• Healthy male between 20 to 45 years of age, inclusive at the time of screening
• Additional inclusion criteria apply

Psoriasis subjects

• 20 to 70 years of age, inclusive at the time of screening
• Active but clinically stable, plaque psoriasis
• Psoriasis involving ≥10% of the body surface area
• A minimum PASI score of ≥10 obtained during the screening period
• Additional inclusion criteria apply