JAK1 Inhibitor With Medicated Topical Therapy in Adolescents With Atopic Dermatitis

This is a randomized, double blind, placebo controlled, parallel group, Phase 3 study to
evaluate the efficacy and safety of PF 04965842 in adolescent participants 12 to <18 years of
age with moderate to severe AD. Participants will be screened within 28 days prior to the
first dose of study intervention to confirm study eligibility. Subjects must have
moderate-severe AD involving at least 10% Body Surface Area (BSA); an Investigator Global
Assessment (IGA) score of at least 3; an Eczema Area Severity Index (EASI) of at least 16 and
Peak Pruritus Numerical Rating Score (NRS) of at least 4 on baseline/Day 1. Eligible subjects
will be randomized at the Baseline/Day 1 visit. Approximately 225 participants will be
randomized in a 1:1:1 ratio to receive once daily PF 04965842 at 200 mg, 100 mg, or placebo
for 12 weeks. Randomization will be stratified by baseline disease severity (moderate [IGA =
3] vs. severe [IGA = 4] AD). The investigational products will be administered QD for 12
weeks. Background therapy (medicated and non-medicated topical therapy) must be applied BID
for the duration of the treatment period. The co-primary efficacy endpoints are an IGA score
of clear (0) or almost clear (1) with a reduction from baseline of greater than 2 points at
Week 12 AND an at least 75% improvement of the EASI score (EASI-75) at week 12. Safety and
efficacy assessments will be conducted at the investigator site by a clinical assessor
blinded to treatment assignment. Scheduled clinic or telephone study visits for all subjects
will occur at Screening, Baseline/Day 1, Day 8 (by phone), Day 15, Day 29, Day 43 (by phone),
Day 57, Day 85 (End of treatment/Early termination), Day 113 (End of Study). Participants
discontinuing early from the study will undergo a 4 week follow up period.

This study includes an immunogenicity sub study integrated into the last 4 weeks of the main
study treatment period. At Week 8, up to approximately 90 participants (up to approximately
30 in each treatment arm) who have completed 8 weeks of treatment with study intervention
will receive a tetanus, diphtheria and acellular pertussis combination vaccine (Tdap), and
collection of blood samples for the evaluation of immunogenicity at Weeks 8 and 12.
Participants of this sub study will complete all other protocol specified procedures in the
main study.

At the end of the 12 week study treatment, qualified participants completing the study will
have the option to enter the long term extension (LTE) study B7451015.

Inclusion Criteria:

- Aged between 12 and to 17 with a minimum body weight of 40 kg

- Diagnosis of atopic dermatitis (AD) for at least 1 year and current status of moderate
to severe disease (>= the following scores: BSA 10%, IGA 3, EASI 16, Pruritus NRS
severity 4)

Exclusion Criteria:

- Acute or chronic medical or laboratory abnormality that may increase the risk
associated with study participation

- Unwilling to discontinue current AD medications prior to the study or require
treatment with prohibited medications during the study

- Prior treatment with JAK inhibitors

- Other active non-AD inflammatory skin diseases or conditions affecting skin

- Medical history including thrombocytopenia, coagulopathy or platelet dysfunction,
malignancies, current or history of certain infections, lymphoproliferative disorders
and other medical conditions at the discretion of the investigator

- Pregnant or breastfeeding women, or women of childbearing potential who are unwilling
to use contraception