Study to Evaluate Safety & Efficacy of Topical ATx201 OINTMENT in Adolescents and Adults With Mild to Moderate AD

Inclusion Criteria (main ones): 1. Diagnosis of AD using the Hanifin and Rajka criteria and minimum 1-year history with a current IGA score of 2 or 3 and treatable BSA ≥5% but ≤36% (treatable BSA includes all lesions present at screening except scalp) 2. Age ≥12 and \<60 years 3. Male or nonpregnant and nonlactating female who is abstinent or agrees to use effective contraceptive methods throughout the course of the study. Females must have a negative urine beta-human chorionic gonadotropin hormone (hCG) pregnancy test at Day 1. 4. Subject or LAR able to understand and provide signed informed consent. Assent is also required of adolescents. 5. Normally active and otherwise in good health by medical history and physical examination Exclusion Criteria (main ones): 1. Actively infected AD (ie, requiring antimicrobial therapy as determined by the investigator) 2. Acute exacerbation or flare in the 4 weeks prior to the Day 1 visit that necessitates treatment with a high potency corticosteroid (such as clobetasol propionate or betamethasone dipropionate), or antibiotics, or prednisolone 3. Enrollment in an ATx201 study in the previous 6 months 4. Allergy or history of significant adverse reaction to ATx201 or related compounds, or to any of the excipients used 5. Underlying skin condition that may interfere with the placement of study treatment or impede clinical evaluations (including active Herpes simplex) 6. Current acute or chronic condition unless considered clinically irrelevant and stable by the investigator 7. The presence of a condition the investigator believes would interfere with the ability to provide informed consent or assent, or comply with study instructions, or that might confound the interpretation of the study results or put the subject at undue risk 8. Unable or unwilling to comply with study procedures 9. Exposure to any IP within 30 days prior to randomization There are also some specific criteria related to prior or concomitant therapy