The main purpose of this study is to assess the long-term safety and efficacy of lebrikizumab in participants 6 Months to <18 years of age with moderate-to-severe atopic dermatitis.

This study will last about 68 weeks and may include up to 16 planned visits. If participating in the optional extension as well, the study will last approximately 1 additional year for a total of up to 116 weeks and may include up to 29 scheduled visits.

Inclusion Criteria:

• Received treatment in Study KGBI and have adequately completed the study treatments and last visit of study KGBI, including any applicable systemic AD treatment washout.
• For female participants of childbearing potential, highly effective contraceptive use should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies

Exclusion Criteria:

• Developed an serious adverse events (SAE) during their participation in parent study KGBI deemed related to lebrikizumab, which in the opinion of the investigator or of the medical monitor could indicate that continued treatment with lebrikizumab may present an unreasonable risk for the participant.
• Developed an AE during their participation in the study KGBI that was deemed related to lebrikizumab and led to study treatment discontinuation, which in the opinion of the investigator or of the medical monitor could indicate that continued treatment with lebrikizumab may present an unreasonable risk for the participant.
• Met the criteria for permanent study intervention discontinuation in study KGBI, if deemed related to lebrikizumab or led to investigator- or sponsor-initiated withdrawal of participant from the study (for example, noncompliance, inability to complete study assessments, etc.)

Note: If study KGBI is still blinded at the time of rollover to study KGBJ, conditions deemed related to the study treatment will be considered related to lebrikizumab.

• Are pregnant or breastfeeding or are planning to become pregnant or breastfeed during the study.

Anonymized individual patient level data will be provided in a secure access environment upon approval of a research proposal and a signed data sharing agreement.

Data are available 6 months after the primary publication and approval of the indication studied in the US and European Union (EU), whichever is later. Data will be indefinitely available for requesting.

A research proposal must be approved by an independent review panel and researchers must sign a data sharing agreement.

All participants receive Lebrikizumab during the 16-week blinded treatment period. At Week 18, participants receive open-label lebrikizumab. From Week 52 onward, doses may be blinded or open-label.