The primary objective of the study is to assess the pharmacokinetics (PK) and safety of nemolizumab in pediatric participants (aged 6-23 months) with moderate-to-severe atopic dermatitis (AD) who are not adequately controlled with topical treatments.
Participants greater than and equal to (>=) 6 to less than (<) 24 months of age at the screening visit.
Diagnosis of AD according to the American Academy of Dermatology Consensus Criteria at the time of the screening visit.
Eczema Area and Severity Index (EASI) score >= 16 at both screening and baseline visits.
Investigator's Global Assessment (IGA) score >= 3 (based on the IGA scale ranging from 0 to 4, in which 3 is moderate and 4 is severe) at both screening and baseline visits.
Body weight < 5 Kilograms (kg).
Child in Care: a child placed under the control or protection of an agency, organization, institution, or entity by courts or government authorities under applicable law or regulation.
Cutaneous infection within 1 week before the baseline visit or any infection requiring treatment with oral or parenteral antibiotics, antivirals, antiparasitics, or antifungals within 2 weeks before the baseline visit. Participants may be rescreened once the infection has resolved.Note: A participant with mild, localized superficial infection may be included based on investigator discretion.
Participants who, after a full 16-week treatment course with dupilumab, experienced worsening of AD or failed to achieve minimal improvement (e.g., <= 10% reduction in EASI or no reduction in IGA).