Safety, Tolerability and PK of ATTO-3712 in Healthy Volunteers and Patients With Atopic Dermatitis

Parts 1\&2 (Healthy Volunteers) Key Inclusion Criteria: * Any sex or gender who is 18 to 65 years old, inclusive, at Screening. * Body weight of 50 to 125 kg and body mass index (BMI) between 18.5 and 35 kg/m2 * Considered in good general health based on medical history, physical exam, 12-lead ECG, screening clinical laboratory findings, and vital signs * Negative pregnancy test for participants of child-bearing potential. Part 3 (Participants with Atopic Dermatitis) Key Inclusion Criteria: * Any sex or gender who is 18 to 65 years old * Body weight of 50 to 125 kg and BMI between 18.5 and 40 kg/m2 * Clinically confirmed diagnosis of active AD * History of inadequate response to treatment with topical medications * Baseline weekly mean of daily PP-NRS ≥ 4 at Day 1. * EASI score of ≥ 16 at Screening and Day 1 * vIGA-AD score of ≥ 3 at Screening and Day 1 * ≥10% of body surface area (BSA) affected by AD at Screening and Day 1 * Use of topical bland emollient (moisturizer) at least once daily for at least 5 of the 7 days immediately before Day 1 and agrees to continue using that same emollient at the same frequency throughout the study * Negative pregnancy test for participants of childbearing potential Parts 1 \& 2 (Healthy Volunteers) Key Exclusion Criteria * Any clinically significant underlying illness * History of malignancy within 5 years of Screening * History of major surgery within 8 weeks prior to Day 1 or has a major surgery planned during the study * History of …