Study of ATI-2138 in Adult Participants With Moderate to Severe Atopic Dermatitis

Inclusion Criteria:

• Able to comprehend and willing to sign the IRB approved ICF/assent prior toadministration of study-related procedures.

• Male patients or non-pregnant, non-nursing female patients 18 to 60 years old,inclusive, at the time of informed consent/assent.

• Have at least a 1-year history of moderate or severe AD prior to the ScreeningVisit, and no significant AD flares for the 4 weeks prior to the Screening Visit asdetermined by the Investigator upon review of participant medical history.

Exclusion Criteria:

• Any prior exposure to systemic (oral) JAK inhibitors or TYK inhibitors at any timeprior to Screening.

• Unstable course of AD (spontaneously improving or rapidly deteriorating) based onthe patient history or as determined by the investigator during the ScreeningPeriod.

• Refractory AD (ie, AD that required frequent hospitalizations and/or frequentintravenous treatment for skin infections within the year before the ScreeningVisit).

• Concomitant skin disease or clinically infected AD or presence of other skin diseasein the area to be dosed that may interfere with study assessments.

• Female patients who are pregnant, nursing, or planning to become pregnant during thestudy.