A Study of LY3454738 in Healthy Participants and Participants With Atopic Dermatitis

Phase 1, Multicenter, Randomized, Placebo-Controlled, Triple-Blind, Single-Ascending Dose and Repeat-Dose Trial in Healthy Participants and Participants With Atopic Dermatitis

The main purpose of this study is to investigate the safety, tolerability, and efficacy of the study drug known as LY3454738 in healthy participants and participants with atopic dermatitis. The study has three parts. Each participant will enroll in one part. The study will last 12 to 24 weeks, depending on part.

Inclusion Criteria:

• All: Must have a body mass index of 18.0 to 32.0 kilograms per square meter (kg/m²), inclusive, for Parts A and B, and 18.0 to 45.0 kg/m², inclusive, for Part C and a minimum body weight of 50 kilograms

• For PART A and B only, regarding the inclusion of healthy Japanese participants: Minimum age is 20 years and the participant's biological parents and all of the participant's biological grandparents must be of exclusive Japanese descent and must have been born in Japan

• AD:

  • Must have a diagnosis of AD for at least 12 months with either poor response to topical treatments or inability to use topical treatments
  • Must agree to use moisturizer daily throughout the treatment period

Exclusion Criteria:

• All: must not have previously completed a clinical trial with a molecule targeting interleukin-33 (IL-33) or its receptor

• AD:

  • Must not have received certain topical medications for AD within 2 weeks prior to randomization
  • Must not have received certain oral medications for AD or received phototherapy within 4 weeks prior to randomization
  • Must not have received any antibody-based biologic agents (marketed or investigational) within 5 half lives (t1/2) of the drug prior to randomization
  • Must not have received intravenous, intramuscular, or intra-articular steroids in the past 6 weeks prior to randomization