This study is looking at how well a new medicine, amlitelimab, works and how safe it is for people aged 12 and older with moderate-to-severe atopic dermatitis (a skin condition causing red and itchy skin). The medicine is given as a shot under the skin (subcutaneous injection). The study compares amlitelimab to a placebo, which looks like the medicine but doesn't have any active ingredients. Participants will continue using their usual skin creams, like topical corticosteroids (TCS) or topical calcineurin inhibitors (TCI), during the study.

The study will last up to 44 weeks for those not joining a follow-up study, with 10 visits to the clinic. For those joining the follow-up study, it lasts up to 28 weeks with 9 visits. To join, participants must have had atopic dermatitis for at least a year and have tried other treatments that didn't work well.

• The study is up to 44 weeks long, with 9-10 clinic visits.
• Participants will use amlitelimab or a placebo with their usual skin creams.
• Eligibility includes being 12+ years old and having moderate-to-severe atopic dermatitis.