A Study to Investigate the Efficacy and Safety of Lebrikizumab in Participants With Moderate-to-Severe Atopic Hand and Foot Dermatitis

The main purpose of this study is to assess the efficacy of lebrikizumab versus placebo on skin lesions in adults and adolescent participants with atopic hand and foot dermatitis. This study lasts up to 32 weeks, including a 6-week screening period, a 16-week treatment period, and a safety follow-up visit 12 weeks after the last dose.

Inclusion Criteria: * Have an unequivocal diagnosis of chronic atopic hand and/or foot dermatitis at least 1 year prior to screening, regardless of the extent and severity of concomitant atopic dermatitis (AD) on other areas of the body. AD must be present in at least 2 of the 4 mentioned anatomical areas: left hand, right hand, left foot, or right foot at screening and baseline. * Have a Hand Foot - Investigator Global Assessment (HF-IGA) score of 3 or 4 at the screening and baseline visits. * Have a baseline hand and foot peak pruritus (numeric rating scale) NRS score ≥4. * Have a documented history by the investigator of inadequate response to topical medication(s) (topical corticosteroids (TCIs/TCS), topical PDE-4 inhibitors, or topical janus kinase (JAK) inhibitors) in the treatment of atopic hand foot dermatitis (AHFD) within 6 months of screening, or use of topical medications is medically inadvisable (due to intolerance to treatment, hypersensitivity reactions, significant skin atrophy of hand and feet, and systemic effects, as assessed by the investigator or by the treating physician of the participant). * For adolescent participants, body weight ≥40 kilograms (kg) at baseline. Exclusion Criteria: * Have a positive patch test reaction to 1 or more allergens (a score of 1+ or above according to the International Contact Dermatitis Research Group grading scale) before baseline AND which are deemed to be clinically relevant in the view of the investigator as the current cause of the hand and foot dermatitis. * Have a documented diagnosis of allergic contact dermatitis (ACD) of hands and/or feet, and have a positive patch test reaction at screening, regardless of whether the history of current skin exposure to products containing this allergen (current relevance) is present. * Have a documented or strong clinical suspicion of the diagnosis of protein contact dermatitis of hands and/or feet. These are the participants with occupational or nonoccupational contact with proteins such as food, latex, and so on, who have positive prick test results and present with lesions of contact urticaria or dermatitis on hands and feet. * Have a documented exposure to irritants in the occupational or non-occupational (household/recreational) setting that is believed to be a predominant cause of the current hand and foot dermatitis as per the judgment of the investigator. * Presence of skin comorbidities on hand and/or foot that may interfere with study assessments, such as (but not limited to) palmoplantar psoriasis, palmoplantar keratoderma, impetiginized eczema, lichen planus, pityriasis rubra pilaris, herpes simplex, erythema multiforme, tinea, or scabies. * Have skin comorbidities that may interfere with study assessments. * Treatment with topical medications on the hands and feet within 2 weeks before the baseline visit (except for the use of the participant's own emollients). * Prior treatment with interleukin-13 (IL-13) inhibitors such as lebrikizumab or tralokinumab. * Have received any live attenuated vaccine within less than 4 weeks of the baseline visit or intend to receive a live attenuated vaccine during the study, or within 4 weeks after receiving the last dose of study intervention.