Inclusion Criteria:
All subjects:
1. Male or female subjects aged 18 to 65 years, inclusive, at the time of consent.
2. Subject is willing to participate and is capable of giving informed consent. Note: Consent must be obtained prior to any study-related procedures.
3. Subject must be willing to comply with all study procedures and must be available for the duration of the study.
CHE subjects only:
4. Subject has at least a 6-month history of CHE before Screening (information obtained from medical chart or subject's physician, or directly from the subject).
5. Subject has moderate to severe CHE as defined by an IGA score of ≥3 at Screening and Day 1.
6. Subject has CHE covering ≥0.25% of BSA on palmar surface of hands at Screening and Day 1.
7. Subjects has CHE that can be categorized in one of the following CHE subtypes at Day 1:
- Atopic hand eczema (without wet-work or excessive contact with irritants)
- Irritant contact hand eczema without atopic disease
- Hyperkeratotic hand eczema without atopic disease
- Vesicular hand dermatitis without atopic disease
- Allergic contact hand eczema without atopic disease
- Idiopathic hand eczema without wet-work, excessive contact with irritants, atopic disease, hyperkeratotic morphology, allergic contact hand eczema and vesicular hand eczema.
Subjects with only AD:
8. Subject has clinically confirmed diagnosis of active atopic dermatitis, according to Hanifin and Rajka criteria.
9. Subject has at least a 6-month history of AD and had no significant flares in AD for at least 4 weeks before Screening (information obtained from medical chart or subject's physician, or directly from the subject).
10. Subject has moderate to severe AD as defined by a vIGA-AD score of ≥3 at Screening and Day 1.
11. Subject has AD covering ≥0.5% of BSA at Screening and Day 1.
12. Subject has an AD lesion covering ≥0.25% of BSA on the forearm at Screening and Day 1.Healthy Volunteers only:
13. Subject is in good general health, according to the investigator's judgment based on medical history and physical examination.
Exclusion Criteria:
All subjects:
1. Subject has a history of skin disease or presence of skin condition that, in the opinion of the investigator, would interfere with the study assessments.
2. Subject has used systemic antibiotics within 2 weeks prior to Day 1.
3. Subject has used topical antibiotics within 1 week prior to Day 1.
4. Subject has used topical products containing urea or salicylic acid within 1 week prior to Day 1.
5. Subject has received any marketed or investigational biological agent within 12 weeks or 5 half-lives (whichever is longer) prior to Day 1.
6. Subject is currently receiving a nonbiological investigational product or device or has received one within 4 weeks prior to Day 1.
7. Subject has had excessive sun exposure, is planning a trip to a sunny climate, or has used tanning booths within 4 weeks prior to Day 1. Use of sunscreen products are recommended when exposure cannot be avoided.
8. Subject is a female who is pregnant or who is planning to become pregnant during the study.
CHE subjects only:
9. Subject has clinically infected chronic hand eczema on hands and/or wrists.
10. Subject with suspected or proven hand eczema protein contact dermatitis.
11. Subject has used doxepin within 1 week prior to Day 1.
12. Subject has used hydroxyzine or diphenhydramine within 1 week prior to Day 1.
13. Subject has used any topical medicated treatment that could affect CHE within 1 week prior to Day 1, including, but not limited to, topical corticosteroids, topical retinoids, crisaborole, calcineurin inhibitors, tars, antimicrobials, medical devices, and bleach baths.
14. Subject has used alitretinoin, isotretinoin, acitretin or other systemic retinoids within 4 weeks before Day 1, or has not completely recovered from its side effects.
15. Subject has used systemic treatments (other than biologics) that could have an impact on CHE less than 4 weeks prior to Day 1 (eg, calcineurin inhibitors, methotrexate, cyclosporin, hydroxycarbamide \[hydroxyurea\], azathioprine), or systemic steroids (including oral or injectable corticosteroids).
Note: Intranasal corticosteroids, eye or ear drops containing corticosteroids, and inhaled corticosteroids for stable medical conditions are allowed.
16. Subject has used dupilumab within 12 weeks prior to Day 1.
17. Subject has received any UV-B phototherapy (including tanning beds) or excimer laser within 4 weeks prior to Day 1.
18. Subject has had psoralen-UV-A (PUVA) treatment within 4 weeks prior to Day 1.
Subjects with only AD:
19. Subject has clinically infected AD.
20. Subject has AD lesion on hand and/or feet at screening or Day 1.
21. Subject has received an intravenous immunoglobulin (IVIg) therapy within 12 weeks prior to Day 1.
22. Subject has used doxepin within 1 week prior to Day 1.
23. Subject has used hydroxyzine or diphenhydramine within 1 week prior to Day 1.
24. Subject has used any topical, medicated treatment that could affect AD within 1 week prior to Day 1, including, but not limited to, topical corticosteroids, crisaborole, calcineurin inhibitors, ruxolitinib, tars, antimicrobials, medical devices, and bleach baths.
25. Subject has used systemic treatments (other than biologics) that could affect AD less than 4 weeks prior to Day 1, including, but not limited to, retinoids, calcineurin inhibitors, methotrexate, cyclosporine, hydroxycarbamide (hydroxyurea), azathioprine, oral/injectable corticosteroids, baricitinib, upadacitinib, and abrocitinib.
26. Subject has used dupilumab within 12 weeks prior to Day 1.
27. Subject has received any UV-B phototherapy (including tanning beds) or excimer laser within 4 weeks prior to Day 1.
28. Subject has had PUVA treatment within 4 weeks prior to Day 1. Note: Intranasal corticosteroids and inhaled corticosteroids are allowed. Eye and ear drops containing corticosteroids are allowed.
29. Subject has used tralokinumab within 12 weeks prior to Day 1.
Healthy Volunteers only:
30. Subject has history of atopic dermatitis, allergic rhinitis, or asthma.