This is a double-blind, multicenter study to assess the efficacy and safety of E6201 topical administration to pre-identified marker lesions in adult subjects with chronic plaque type psoriasis. Treatment duration is 8 weeks, followed by a 4-week period without treatment. Pharmacokinetic samples will be obtained pre-and post treatment.

INCLUSION CRITERIA:

• Males and females 18 years or older with a clinical diagnosis of mild-to-moderate plaque-type psoriasis for ≥12 months prior to screening
• Female participants postmenopausal >1 year or surgically sterile
• Two representative and similar target lesions for the condition, each of 15-25 centimeters squared (cm^2), up to 50 cm^2 in surface area
• Target lesion severity score of 4-8 on a scale of 0 to 12, where, in the opinion of the Investigator, 0 equals no evidence of disease and 12 equals severe induration, erythema, scaling, and pruritus
• Prescription medications, if applicable, for chronic conditions allowed but must be on a stable regimen prior to and during the study; this is also applicable for dietary supplements and over-the-counter (OTC) drugs
• Participants able and willing to give informed consent

EXCLUSION CRITERIA

• Use of any, concomitant, topical treatment for psoriasis, excluding emollients
• Use of any, concomitant, systemic treatment for psoriasis, including ultraviolet radiation (UVR) light
• Evidence of significant hepatic, gastrointestinal, renal, respiratory, endocrine, hematological, neurological, psychiatric, musculoskeletal, rheumatologic, or cardiovascular system abnormalities
• Evidence of any clinically significant deviation from normal with respect to medical history, physical examination, vital signs, 12-lead electrocardiogram (ECG), or clinical laboratory determinations. If any participant has an abnormal clinical laboratory test finding that meets specified criteria, that participant will be re-tested by repeated blood draw and clinical laboratory assessment. If the abnormal test finding is confirmed, the participant will be excluded from the study.