A Trial of a Botanical Drug (EISO) for Treatment of Mild-to-Moderate Plaque Psoriasis

Inclusion Criteria: * Are ≥18 but ≤65 years of age * Have a clinical diagnosis of mild-to-moderate plaque psoriasis, as defined by a Psoriasis Area and Severity Index (PASI) score between 2 and 12, appropriate for topical treatment that covers a minimum of 1.0% and a maximum of 10% Body Surface Area (BSA), in the permitted treatment areas. * Are willing to treat all psoriasis occurring in the permitted treatment areas with only SAN021 * Are free of any systemic or dermatologic disorder, which, in the opinion of the investigator, will interfere with the study results or increase the risk of adverse events. * Are willing to avoid prolonged exposure of the treatment area to ultraviolet radiation (natural or artificial) for the duration of the study. * Are willing to refrain from using any lotions, moisturizer, cleansers, cosmetics or creams, other than those issued as part of the study, on the treatment areas during the treatment period. * If female of childbearing potential, must be willing to practice an acceptable form of birth control for the duration of the study. * Are able to give written informed consent in a manner approved by the Institutional Review Board or Ethics Review Committee and comply with the requirements of the study. * Are willing to avoid participation in any other interventional clinical trial for the duration of this study. * Are willing to refrain from treating restricted areas, which will be excluded from the PGA assessments and Body Surface Area (BSA) calculation. These areas are as follows: head, neck, fingernails, toenails, soles of feet, and palms of hands, axillae, or intertriginous areas. Exclusion Criteria: * Have spontaneously improving or rapidly deteriorating plaque psoriasis, or pustular psoriasis as determined by the Investigator. * Have been treated, with prescription medication for plaque psoriasis, with no improvement in condition, within 60 days prior to the Baseline visit. * Are pregnant, breast-feeding, or planning to become pregnant during the study. * Have any evidence of systemic cancer, squamous cell carcinoma, basal cell carcinoma, in the last 5 years, or any other confounding skin condition. * Are undergoing treatments with topical antipsoriatic drug products other than corticosteroids within 14 days prior to the Baseline Visit, and for therapy containing corticosteroids or retinoids within 28 days prior to Baseline Visit. * Have open sores or open lesions in the treatment area(s). * Have any condition that, in the opinion of the investigator, would confound the safety and/or efficacy assessments of plaque psoriasis. * Have participated in any interventional clinical trial in the previous 30 days. * Have a known sensitivity to any of the constituents of the test product including sensitivities to sandalwood oil, fragrances, or any member of the Compositae family of vascular plants (e.g., sunflowers, daisies, dahlias, etc.). * Have used, are using, or are planning to use immunosuppressive or immunomodulatory medication (i.e., biologics), including oral or parenteral corticosteroids. * Have a history of alcohol or illegal drug/substance abuse, or suspected alcohol or illegal drug/substance abuse in the past 2 years. * Plan to seek alternative treatment of any kind for their psoriasis, in the eligible treatment areas or otherwise, during the trial period.