 This is a two-center, randomized, placebo- and active comparator-controlled trial that will be double-blind for the investigational products IPs and observer-blind for the active comparator with intra-individual comparison of treatments. Twelve male and post-menopausal female volunteer subjects, aged 18 years or older, with psoriasis vulgaris and mild or moderate chronic plaques in a stable phase and an area sufficient for six treatment fields, will be enrolled. SOR007 Ointment will be administered topically at four concentrations 0.15, 0.3, 1, and 2, in addition to a placebo ointment SOR007 without the active pharmaceutical ingredient and an active comparator, Taclonex Ointment calcipotriene 0.005 and betamethasone dipropionate 0.064 . Treatments will be administered once daily, 10 times over a 12-day trial period. Assessments will include safety, pharmacokinetics PK, and preliminary efficacy as determined by measurement of psoriatic infiltrate using 22-megahertz MHz sonography as well as clinical scoring on a 5-point scale. Subjects who withdraw early for reasons unrelated to investigational product adverse events AEs will be replaced. 