Safety, Pharmacokinetics and Efficacy of ARQ-151 Cream in Adults With Mild to Moderate Chronic Plaque Psoriasis

This study assessed the safety and pharmacokinetics (PK) of a single dose application of ARQ-151 cream 0.5% to 25 cm\^2 of psoriatic plaque(s) (Cohort 1). The study also assessed the safety, PK and efficacy of ARQ-151 cream 0.5% vs vehicle and ARQ-151 cream 0.15% vs vehicle applied once a day for 28 days to individuals with 0.5% to 5.0% body surface area (BSA) of chronic plaque psoriasis (Cohort 2).

There were 2 cohorts of participants. Cohort 1 was a single dose study of ARQ-151 0.5% cream applied to 25 cm\^2 of psoriatic plaque(s) in 8 psoriasis participants. Cohort 2 was a parallel group, double blind, vehicle controlled study in which ARQ-151 cream 0.5%, ARQ-151 cream 0.15% or vehicle cream was applied once a day for 28 days to participants with between 0.5% to 5.0% BSA of chronic plaque psoriasis. Participants were adult (≥18 years old) males or females with chronic plaque psoriasis.

Eligibility Criteria:
Inclusion Criteria:

* Adult male and female participants aged ≥18 years.
* In Cohort 1, participants must have at least 25 cm\^2 of chronic plaque psoriasis (excluding the face, scalp, intertriginous areas, palms and soles).
* In Cohort 2, participants must have 0.5% to 5.0% of total BSA of chronic plaque psoriasis and at least one target plaque, of at least 9 cm\^2 in size with a TPSS ≥4 (excluding the face, scalp, intertriginous areas, palms and soles).
* Women of childbearing potential must have a negative urine pregnancy test at Screening and agree to use birth control throughout the trial.
* In good health as judged by the Investigator, based on medical history, physical examination, 12-lead electrocardiogram (ECG), serum chemistry labs, hematology values, and urinalysis.
* Participants agree not to have prolonged sun exposure during the course of the study. Tanning bed use is not allowed.
* Participants are competent to sign and give informed consent and considered reliable and capable of adhering to the Protocol and visit schedule.

Exclusion Criteria:

* Participants with non-plaque forms of psoriasis (erythrodermic, guttate, pustular or palmo-plantar psoriasis) or with drug-induced psoriasis.
* Evidence of skin conditions other than psoriasis that would interfere with evaluation of the effect of the study medication.
* Pregnant or lactating women or women planning to become pregnant during the study and / or within 28 days following the last dose of study medication.
* Known allergies to excipients in ARQ-151 cream.
* Participants who cannot discontinue the use of strong P-450 cytochrome inducers or inhibitors for two weeks prior to the baseline visit and during the study period.
* Participants who are unwilling to refrain from using a tanning bed for 2 weeks before and during the study.
* Participants who cannot discontinue systemic therapies and/or topical therapies for the treatment of psoriasis.
* Participants with a history of chronic alcohol or drug abuse in past 6 months.
* History of and/or concurrent condition of serious hypersensitivity (anaphylactic shock or anaphylactoid reaction) to phosphodiesterase type 4 (PDE-4) inhibitors.
* Current or a history of cancer within 5 years with the exception of fully excised skin basal cell carcinoma, cutaneous squamous cell carcinoma or carcinoma in situ of the cervix.
* Participants with active infection that requires oral or intravenous administration of antibiotics, antifungal or antiviral agents.
* Participants who are unable to communicate, read or understand language, or who display another condition which makes them unsuitable for clinical study participation.