A Study Assessing the PK, PD, Safety, and Tolerability of SB414 in Psoriasis

Inclusion Criteria: * Be male or female, 18-70 years old, and in good general health; * Have a clinical diagnosis of stable chronic plaque psoriasis of mild to moderate severity based on the PSGA, involving 2-15% BSA (excluding the scalp/face), present for \> 6 months; * Must have at least 2 target plaques on trunk and/or extremities at least 5 cm2 with a TPSS \> 5 and thickness sub-score \> 2. Target plaques cannot be located on the groin, hands, feet, neck, face, elbows, knees, ankles or scalp; * Be willing to not use any other systemic agents used to treat psoriasis or apply any other topical products (medicated or over-the-counter) to the treatment sites on the trunk and/or extremities during the study; * Women of childbearing potential (WOCBP) must have a negative UPT prior to randomization and must agree to use an effective method of birth control during the study and for 30 days after their final study visit. Exclusion Criteria: * Have inverse (i.e.: axillae, groin) or facial psoriasis only, erythrodermic psoriasis, guttate psoriasis, pustular psoriasis, drug-induced psoriasis, and /or psoriatic arthritis requiring treatment with disease modifying antirheumatic drugs (DMARDs); * Concurrent or recent use of topical or systemic medications without a sufficient washout period; * Are immunocompromised, including those who are known HIV positive or received immunosuppressive treatment within the past 6 months; * Female subjects who are pregnant, nursing mothers, or planning to become pregnant during the study.