The percentage of participants who discontinued from study treatment due to 1 or more AEs assessed is summarized cumulatively. A summary of all SAE's, regardless of causality, is located in the Reported Adverse Events section.

All enrolled participants.

The IGA measures the investigator's global assessment of the participant's overall severity of their AD, based on a static, numeric 5-point scale from 0 (clear skin) to 4 (severe disease). The score is based on an overall assessment of the degree of erythema, papulation/induration, oozing/crusting, and lichenification.

All participants with evaluable data for IGA score of 0 or 1.

The EASI assesses objective physician estimates of 2 dimensions of atopic dermatitis - disease extent and clinical signs affected: 0 = 0%; 1 = 1-9%; 2 = 10-29%; 3 = 30-49%; 4 = 50-69%; 5 = 70-89%; 6 = 90-100% and the severity of 4 clinical signs: (1) erythema, (2) edema/papulation, (3) excoriation, and (4) lichenification each on a scale of 0 to 3 (0 = none, absent; 1 = mild; 2 = moderate; 3 = severe) at 4 body sites (head/neck, trunk, upper limbs, and lower limbs). Half scores are allowed between severities 1, 2, and 3. The final EASI score was obtained by weight-averaging these 4 scores and will range from 0 to 72 (severe).

The EASI responder is defined as a participant who achieves a ≥ 75% improvement from baseline in the EASI score.

All participants with evaluable data for EASI-75.

The EASI assesses objective physician estimates of 2 dimensions of atopic dermatitis - disease extent and clinical signs affected: 0 = 0%; 1 = 1-9%; 2 = 10-29%; 3 = 30-49%; 4 = 50-69%; 5 = 70-89%; 6 = 90-100% and the severity of 4 clinical signs: (1) erythema, (2) edema/papulation, (3) excoriation, and (4) lichenification each on a scale of 0 to 3 (0 = none, absent; 1 = mild; 2 = moderate; 3 = severe) at 4 body sites (head/neck, trunk, upper limbs, and lower limbs). Half scores are allowed between severities 1, 2, and 3. The final EASI score was obtained by weight-averaging these 4 scores and will range from 0 to 72 (severe).

All participants with evaluable data for EASI score.

The EASI assesses objective physician estimates of 2 dimensions of atopic dermatitis - disease extent and clinical signs affected: 0 = 0%; 1 = 1-9%; 2 = 10-29%; 3 = 30-49%; 4 = 50-69%; 5 = 70-89%; 6 = 90-100% and the severity of 4 clinical signs: (1) erythema, (2) edema/papulation, (3) excoriation, and (4) lichenification each on a scale of 0 to 3 (0 = none, absent; 1 = mild; 2 = moderate; 3 = severe) at 4 body sites (head/neck, trunk, upper limbs, and lower limbs). Half scores are allowed between severities 1, 2, and 3. The final EASI score was obtained by weight-averaging these 4 scores and will range from 0 to 72 (severe).

The EASI responder is defined as a participant who achieves a ≥ 50% improvement from baseline in the EASI score.

All participants with evaluable data for EASI-50.

The EASI assesses objective physician estimates of 2 dimensions of atopic dermatitis - disease extent and clinical signs affected: 0 = 0%; 1 = 1-9%; 2 = 10-29%; 3 = 30-49%; 4 = 50-69%; 5 = 70-89%; 6 = 90-100% and the severity of 4 clinical signs: (1) erythema, (2) edema/papulation, (3) excoriation, and (4) lichenification each on a scale of 0 to 3 (0 = none, absent; 1 = mild; 2 = moderate; 3 = severe) at 4 body sites (head/neck, trunk, upper limbs, and lower limbs). Half scores are allowed between severities 1, 2, and 3. The final EASI score was obtained by weight-averaging these 4 scores and will range from 0 to 72 (severe).

The EASI responder is defined as a participant who achieves a ≥ 90% improvement from baseline in the EASI score.

All participants with evaluable data for EASI-90.

The BSA affected by AD will be assessed for 4 separate body regions: head and neck, trunk (including genital region), upper extremities, and lower extremities (including the buttocks). Each body region will be assessed for disease extent ranging from 0% to 100% involvement. BSA was calculated using the participant's palm using the 1% rule, 1 palm was equivalent to 1% with estimates of the number of palms it takes to cover the affected AD area. Maximum number of palms were 10 palms for head and neck (10%), 20 palms for upper extremities (20%), 30 palms for trunk, including axilla and groin (30%), 40 palms for lower extremities, including buttocks (40%). Percent of BSA for a body region was calculated as = total number of palms in a body region * % surface area equivalent to 1 palm. Overall percent BSA of all 4 body regions ranges from 0% to 100 % with higher values representing greater severity of AD.

All participants with evaluable data for BSA.

PROMIS® is a set of person-centered measures that evaluates and monitors physical, mental, and social health in adults and children. Participants ≤17 years will complete pediatric versions for the duration of the study. PROMIS anxiety has 8 questions on Emotion Distress-Anxiety (or Pediatric Anxiety Symptom). Each question has 5 response options with values from 1 to 5. Total raw scores were converted to T-Scores (mean = 50 and a standard deviation = 10) with higher scores representing greater anxiety.

All participants with evaluable data for PROMIS Anxiety.

PROMIS is a set of person-centered measures that evaluates and monitors physical, mental, and social health in adults and children. The PROMIS measures will be completed by the participant in the study clinic. PROMIS depression has 8 questions on Emotion Distress-Depression. Questions are measured on a 5-point scale with 1 being "Never" and 5 being "Always". Responses for each section will be summed and converted to T-Scores using the Assessment Center PROMIS Scoring Service, which rescales the raw score to a standardized T-Score with a population mean of 50 and a standard deviation of 10. Total raw scores were converted to T-scores with higher scores indicating greater severity of symptoms.

All participants evaluable data for PROMIS Depression.

The DLQI questionnaire designed for participants aged 17 years or more is a 10-item, validated questionnaire used to assess the impact of skin disease on the quality of life of an affected person. The 10 questions cover the following topics: symptoms, embarrassment, shopping and home care, clothes, social and leisure, sport, work or study, close relationships, sex, and treatment, over the previous week. Response categories include "Not at all," "A little," "A lot," and "Very much," with corresponding scores of 0, 1, 2, and 3 respectively. Questions 3-10 also have an additional response category of "Not relevant" which is scored as "0". Questions are scored from 0 to 3, giving a possible total score range from 0 (no impact of skin disease on quality of life) to 30 (maximum impact on quality of life). A high score is indicative of a poor quality of life.

All participants with evaluable data for DLQI.

The CDLQI questionnaire is designed for use in children (4 to 16 years of age). It consists of 10 items that are grouped into 6 domains: symptoms & feelings, leisure, school or holidays, personal relationships, sleep, & treatment. The scoring of each question is: Very much =3; Quite a lot = 2; Only a little = 1; Not at all = 0. CDLQI total score is calculated by summing all 10 items responses and has a range of 0 to 30 (higher scores are indicative of greater impairment).

All participants with evaluable data for CDLQI.

Pharmacokinetics (PK): Average Serum Concentration of Lebrikizumab was evaluated at Week 52.

All participants with evaluable PK data at Week 52.