The purpose of this study is to evaluate the study drug, SYX-5219, in a multi-part First-in-Human (FiH) study to be conducted in healthy volunteers and participants with Atopic Dermatitis (AD). The objectives of this study are to determine the safety, tolerability and levels of SYX-5219 in the blood and urine when SYX-5219 is given in each part of the study (SAD, MAD, Food Effect and Participants with AD).
The study will be split into up to 3 parts as follows:
* Part 1 - Single Ascending Dose (SAD) and Food Effect in healthy volunteers * Part 2 - Multiple Ascending Dose (MAD) in healthy volunteers * Part 3 - Multiple Dose in Participants with AD - enrolling up to 45 males and females with a confirmed diagnosis of AD of at least 6 months, evaluating multiple dose administrations of SYX-5219 or placebo daily over a period of 42 days.
Healthy male and female participant, between ≥ 18 to ≤ 65 years of age, inclusive, with a BMI of body mass index (BMI) of 18-32 kg/m2.
Female participant of non-childbearing potential or female of childbearing potential that is sexually abstinent.
No clinically significant abnormalities in laboratory, vital signs or ECG measurements.
Male and female participants with clinically confirmed diagnosis of active AD, between ≥ 18 to ≤ 65 years of age, inclusive, with a BMI of body mass index (BMI) of ≤40 kg/m2.
Any clinically significant medical condition or physical/laboratory/ECG/vital signs abnormality that would, in the opinion of the Investigator, put the participant at undue risk.
Has medical history as stated in the main study exclusion criteria.
Received treatment(s) as stated in the main study exclusion criteria.