This is a single-arm, open-label study that will examine the effect of abrocitinib in subjects with atopic dermatitis.

This study is being conducted to evaluate the efficacy, safety, and molecular effects of abrocitinib in subjects with an unsatisfactory response or facial erythema after at least 12 weeks of treatment with dupilumab. Approximately 60 subjects with atopic dermatitis will receive abrocitinib once daily for 12 weeks.

Inclusion Criteria:

1. Male or female subject 18 years of age or older, at the time of consent.

2. Subject has clinically confirmed diagnosis of active atopic dermatitis (AD), according to Hanifin and Rajka criteria.

3. Subject has at least a 1-year history of AD and had no significant flares in AD for at least 4 weeks before screening.

4. Subjects who had moderate to severe AD before initiating dupilumab treatment.

5. Subject currently has an unsatisfactory response or facial erythema after at least 12 weeks of treatment with dupilumab, defined as follows:

   1. A global vIGA-AD ≥ 2, at least 1% BSA with facial erythema, and a modified vIGA-AD for the face ≥2 at screening and Day 1 OR
   2. A global vIGA-AD ≥ 2, at least 3% BSA affected by AD on the trunk and/or limbs, and a modified vIGA-AD for the trunk/limbs ≥ 2 at screening and Day 1.

Exclusion Criteria:

1. Subject is a female who is breastfeeding, pregnant, or who is planning to become pregnant during the study.
2. Subject has clinically infected AD.
3. Subject has a history of skin disease or presence of skin condition that would interfere with the study assessments.
4. Subject has a history of cancer within 5 years prior to Day 1.
5. Subject has a history of lymphoproliferative disorder, lymphoma, or leukemia, or signs and symptoms suggestive of current lymphatic or lymphoid disease.
6. Subject has any clinically significant medical condition that would, in the opinion of the investigator, put the subject at undue risk or interfere with interpretation of study results.
7. Subject is known to have immunodeficiency disorder or a first-degree relative with a hereditary immunodeficiency.
8. Subject has a current or recent clinically serious infection.
9. Subject has used abrocitinib prior to Day 1.
10. Subject has a known hypersensitivity to abrocitinib or its excipients.
11. Subject has a known history of clinically significant drug or alcohol abuse within 6 months prior to Day 1 that in the opinion of the investigator will preclude participation in the study.