• Part 1 only: Adult participants between 18 to 55 years of age, inclusive, at the time of signing the ICD

• Part 2 only: Adult participants, who at the time of screening, are between the ages of 18 and 70 years, inclusive. Participants above 65 years need to be discussed with the sponsor.

• Part 1 only: Participants who are overtly healthy as determined by medical evaluation including medical history, physical examination, vital sign assessments, temperature, 12-lead ECGs, laboratory tests

• BMI of 17.5 to 40 kg/m2; and a total body weight \>50 kg (110 lbs)

• Part 2 only: Must meet the following AD criteria:

‣ Have a clinical diagnosis of chronic AD (also known as atopic eczema) for approximately 1 year prior to Day 1 and have the diagnosis of AD confirmed by photographs (at screening) and diagnostic criteria for AD.

⁃ Either have had an inadequate response to treatment with topical medications (for at least 4 consecutive weeks within 1 year of the first dose of the study intervention). OR Have a documented reason why topical treatments are considered medically inappropriate within the last year.

⁃ Have moderate to severe AD (defined as having an affected BSA (captured as part of EASI) ≥10%, IGA ≥3, and EASI ≥12 at both the screening and baseline visits).

⁃ Have an otherwise healthy medical evaluation (other than signs and symptoms of AD) including medical history, physical examination, vital sign assessments, temperature, 12-lead ECGs, laboratory tests.

∙ Mild or moderate asthma that is well-controlled (not requiring high dose inhaled corticosteroids, systemic \[oral or parenteral\] corticosteroids, or biologic asthma treatments).