Inclusion Criteria:  Male or female, aged 18 to 75 years (inclusive) Have a diagnosis of plaque type psoriasis for ≥ 6 months Must have chronic plaque type psoriasis of moderate severity All subjects must agree and commit to the use of a reliable contraceptive regimen.  Exclusion Criteria:  Current diagnosis of forms of psoriasis other than chronic plaque type only Drug-induced psoriasis Other inflammatory skin disease that may confound the evaluation of plaque psoriasis Failed 2 or more systemic treatments for plaque psoriasis Medicinal shampoos that contain tar and/or salicylic acid within 2 weeks prior to Baseline Visit