A First-in-human Study to Investigate Single Doses of DCY636 in Healthy Volunteers and Multiple Doses in Participants With Moderate to Severe Atopic Dermatitis

Key Inclusion Criteria: Healthy Participants (Part 1) • Healthy male and non-childbearing potential female participants 18 to 55 years of age inclusive. Participants with moderate to severe atopic dermatitis (Part 2) * Males and non-pregnant females age 18 years or older * Diagnosis of atopic dermatitis for at least 1 year not adequately controlled by topicals * Moderate to severe atopic dermatitis as defined by all of the following: * EASI score ≥12 at screening visit and ≥16 at baseline (BL) visit * IGA score ≥3 at screening visit and baseline visit * Total Body surface area (BSA) affected by AD ≥ 10 % at screening visit and baseline visit * Peak Pruritus NRS score ≥4 at baseline visit, based on weekly average of daily assessment in the week prior to baseline visit Key Exclusion Criteria: All Participants (Part 1, Part 2) * Use of other investigational drugs within the last 30 days or 5 half-lives of the other drugs prior to initial dosing, whichever is longer. * Meet any of the prohibited medication use criteria at baseline visit. * A positive syphilis test result during screening period. * Evidence of active or latent TB infection, as determined by T-Spot test during screening period. * History of immunodeficiency diseases, or a positive human immunodeficiency virus (HIV) test result. * Recent (within last half year) or ongoing helminth infection. * History of hepatitis B or hepatitis C or serologic evidence for viral hepatitis. A positive Hepatitis B viru…