Phase 2a Study of the Safety, Tolerability, and Pharmacokinetics of Topically Administered PRN473 (SAR444727) in Patients With Mild to Moderate Atopic Dermatitis

Study duration per patient is approximately 56 days including a 42-days treatment period.

Inclusion Criteria:

• Male and female adults 18 to 70 years of age (inclusive) at the time of informed consent.
• Diagnosed with mild to moderate AD.
• History of AD for at least 6 months as determined by the Investigator through patient interview.
• Stable disease for the 4 weeks prior to the screening visit with no significant flares in AD as determined by the Investigator.
• Validated Investigator Global Assessment-atopic dermatitis (vIGA-AD) score of Moderate or Mild at Screening. The vIGA-AD is evaluated for the entire body except scalp, palms, soles and genitals.
• Has AD involvement (excluding scalp, palms, soles and genitals) of at least 1.0% BSA and no more than 14.0% BSA.
• Has at least two target lesions 100 cm2 or greater with a difference no greater than 1 point in lesion TSS and at least 5 cm apart located on the trunk (excluding genitals) or upper extremities (excluding palms).
• If female, patients with child-bearing potential must have a negative pregnancy test, and agree to practice true abstinence or agree to use highly effective contraception.
• If male, agree to use a male condom and highly effective contraception with female partners of child-bearing potential.
• In good health as judged by the Investigator.

Exclusion Criteria:

• Patients who have failed 2 or more prior systemic treatments for AD.
• Patients who have received a live or attenuated vaccine in the last 12 weeks or intend to receive a live or attenuated vaccine during the study.
• Patients who cannot discontinue prohibited medications and treatments prior to the Baseline visit and during the study.
• Has unstable AD, based on the judgement of the Investigator, or any consistent requirement for high potency topical steroids to manage AD signs or symptoms.
• Patients who have significant active systemic or localized bacterial, viral, fungal, and helminth infection in the last 30 days.
• Patients unwilling to refrain from prolonged sun exposure or use of a tanning bed or other artificial light emitting devices for 4 weeks prior to Baseline and during the study.
• Patients with other skin conditions that would interfere with evaluations of the effect of the study medication on AD, as determined by the Investigator.
• Patients with known genetic dermatological conditions that overlap with AD, such as Netherton syndrome.
• Previous use of a BTK inhibitor.
• Women who are pregnant, wishing to become pregnant during the study, or are breastfeeding.
• Patients currently undergoing allergy (eg, food allergy testing or skin prick testing), patch testing, or food challenges, or plan to do so during the study.
• Patients who have undergone major surgery within 4 weeks prior to Day 1 or patients who have a major surgery planned during the study.
• Regular use of drugs of abuse or regular alcohol consumption within 6 months prior to the study.