Safety, Pharmacokinetics and Efficacy of Dupilumab in Patients ≥6 Months to <6 Years With Severe Atopic Dermatitis (Liberty AD PRESCHOOL)

1. Part A (open-label, single-ascending-dose, sequential cohort phase 2 study):

- Primary objective is to characterize the safety and PK of dupilumab administered as
a single dose in pediatric participants, 6 months to less than 6 years of age, with
severe AD.

- Secondary objective is to evaluate the efficacy and immunogenicity of a single dose
of dupilumab in participants 6 months to less than 6 years of age with severe AD

2. Part B (randomized, double-blind, parallel-group, placebo-controlled phase 3 study):

- Primary objective is to demonstrate the efficacy of multiple doses of dupilumab
over 16 weeks of treatment when administered concomitantly with topical
corticosteroids (TCS) in pediatric participants, 6 months to less than 6 years of
age, with severe AD.

- Secondary objective is to assess the safety and immunogenicity of multiple doses of
dupilumab over 16 weeks of treatment when administered concomitantly with TCS in
participants 6 months to less than 6 years of age with severe AD

Key Inclusion Criteria

1. Diagnosis of AD according to the American Academy of Dermatology consensus criteria at
the screening visit

2. Participants with documented recent history (within 6 months before the screening
visit) of inadequate response to topical AD medication(s)

3. IGA = 4 at screening and baseline visits

4. EASI ≥21 at screening and baseline visits

5. Body Surface Area (BSA) ≥15% at screening and baseline visits

Key Exclusion Criteria

1. Participation in a prior dupilumab clinical study

2. History of important side effects of medium potency topical corticosteroids (only
applicable for part B of the study)

3. Having used immunosuppressive/immunomodulating drugs within 4 weeks before the
baseline visit

4. Treatment with a live (attenuated) vaccine within 4 weeks before the baseline visit

5. Active chronic or acute infection requiring treatment with systemic antibiotics,
antivirals, antiprotozoals, or antifungals within 2 weeks before the baseline visit.

6. Known history of human immunodeficiency virus (HIV) infection or HIV seropositivity at
the screening visit

7. History of malignancy at any time before the baseline visit

8. Diagnosed active endoparasitic infections or at high risk of these infections

9. Severe concomitant illness(es) that, in the investigator's judgment, would adversely
affect the patient's participation in the study

Note: Other protocol defined Inclusion/ Exclusion criteria apply