This is a Phase 2b study to determine the safety, tolerability, pharmacokinetic (PK), and efficacy of ATI-1777 in patients 12 to 65 years old with mild to severe Atopic Dermatitis. Eligible participants will apply either ATI-1777 or Vehicle Topical Solution once daily or twice daily for 4 weeks.

Inclusion Criteria:

1. Able to comprehend and willing to sign the IRB approved ICF/assent prior to administration of study-related procedures.
2. Male patients or non-pregnant, non-nursing female patients 12 to 65 years old, inclusive, at the time of informed consent/assent.
3. Have at least a 6-month history of AD prior to the Screening Visit, and no significant AD flares for the 4 weeks prior to the Screening Visit.

Exclusion Criteria:

1. Unstable course of AD (spontaneously improving or rapidly deteriorating) based on the patient history or as determined by the investigator during the Screening Period.
2. Concomitant skin disease or clinically infected AD or presence of other skin disease in the area to be dosed that may interfere with study assessments.
3. Female patients who are pregnant, nursing, or planning to become pregnant during the study.

Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)