The Mayo Clinic Score (MCS) ranges from 0 to 12 and is a composite of 4 assessments (each rated from 0-3): stool frequency, rectal bleeding, endoscopy, and physician's global assessment. Higher scores represent greater disease severity. Remission was defined as MCS less than or equal to (≤)2 with individual subscores ≤1 and a rectal bleeding subscore of 0.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in Cohort 2 who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation.

The MCS ranges from 0 to 12 and is a composite of 4 assessments (each rated from 0-3): stool frequency, rectal bleeding, endoscopy, and physician's global assessment. Higher scores represent greater disease severity. Remission was defined as MCS less than or equal to (≤)2 with individual subscores ≤1 and a rectal bleeding subscore of 0. Clinical Response is MCS with ≥3-point decrease and 30% reduction from baseline as well as ≥1-point decrease in rectal bleeding subscore or an absolute rectal bleeding score of 0 or 1.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in the maintenance phase who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation.

The MCS ranges from 0 to 12 and is a composite of 4 assessments (each rated from 0-3): stool frequency, rectal bleeding, endoscopy, and physician's global assessment. Higher scores represent greater disease severity. Clinical Remission is MCS ≤2 with individual subscores ≤1.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in Cohort 2 who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation.

The MCS ranges from 0 to 12 and is a composite of 4 assessments (each rated from 0-3): stool frequency, rectal bleeding, endoscopy, and physician's global assessment. Higher scores represent greater disease severity. Remission was defined as MCS less than or equal to (≤)2 with individual subscores ≤1 and a rectal bleeding subscore of 0. Clinical Response is MCS with ≥3-point decrease and 30% reduction from baseline as well as ≥1-point decrease in rectal bleeding subscore or an absolute rectal bleeding score of 0 or 1.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in Cohort 2 who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation.

The MCS ranges from 0 to 12 and is a composite of 4 assessments (each rated from 0-3): stool frequency, rectal bleeding, endoscopy, and physician's global assessment. Higher scores represent greater disease severity. Improvement in endoscopic appearance of the mucosa is Endoscopy subscore ≤1.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in Cohort 2 who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation.

The MCS ranges from 0 to 12 and is a composite of 4 assessments (each rated from 0-3): stool frequency, rectal bleeding, endoscopy, and physician's global assessment. Higher scores represent greater disease severity. Endoscopic Remission is Endoscopy subscore = 0.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in Cohort 2 who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation.

Nancy Histological Index (NHI) is a 5-level classification ranging from grade 0 (No histologically significant disease) to grade 4 (severely active disease). Histologic remission is defined as a Nancy Histological Index of 0 or 1.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in Cohort 2 who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation. Data presented below is only for participants included in the actual analysis.

Rectal bleeding data were collected via the participant's diaries and each day a participant provided a score from 0 to 3 according to the following definitions: 0 = no blood in the stool; 1 = streaks of blood with stool less than half the time; 2 = obvious blood with stool most of the time; 3 = blood alone passed. The Mayo Clinic Score (MCS) rectal bleeding subscore was calculated as the worst value of three days of daily diary scores closest to anchor dates at baseline and post-baseline. The data was considered non-parametric and was reported using RANK analysis of covariance (ANCOVA). Participants were stratified by concomitant treatment with corticosteroids or immunosuppressants at randomization and disease activity measured during screening (MCS ≤9/MCS ≥10); the model adjusted for these stratification factors along with the baseline rectal bleeding (RB) subscore.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in Cohort 2 who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation. Data presented below is only for participants included in the actual analysis.

Stool frequency data were collected via the participant's diaries and each day a participant provided a score from 0 to 3 according to the following definitions: 0 = normal number of stools; 1 = 1 to 2 more stools than normal; 2 = 3 to 4 more stools than normal; 3 = 5 or more stools than normal. The Mayo Clinic Score (MCS) stool frequency subscore was calculated as the average of three days daily diary scores closest to anchor dates at baseline and post-baseline. The data was considered non-parametric and was reported using RANK analysis of covariance (ANCOVA). Participants were stratified by concomitant treatment with corticosteroids or immunosuppressants at randomization and disease activity measured during screening (MCS ≤9/MCS ≥10); the model adjusted for these stratification factors along with the baseline stool frequency (SF) subscore.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in Cohort 2 who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation. Data presented below is only for participants included in the actual analysis.

The UC-PRO questionnaire is collected in the e-diary and completed by participants for at least 9-12 consecutive days prior to a study visit. The UC-PRO is being reported in three domains; two domains are key endpoints and reported as UC-PRO Signs and Symptoms (UC-PRO/SS). The bowel domain score ranges from 0-27, with a higher score indicating a worse disease state.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in Cohort 2 who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation. Data presented below is only for participants included in the actual analysis.

The UC-PRO questionnaire is collected in the e-diary and completed by participants for at least 9-12 consecutive days prior to a study visit. The UC-PRO is being reported in three domains; two domains are key endpoints and reported as UC-PRO Signs and Symptoms (UC-PRO/SS). The functional (abdominal symptoms) domain score ranges from 0-12, with a higher score indicating a worse disease state.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in Cohort 2 who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation. Data presented below is only for participants included in the actual analysis.

The IBDQ score is a Total Score summed up from across all 32 questions on the questionnaire. The Total Score range is from 32 to 224 with higher scores representing a better quality of life.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in Cohort 2 who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation. Data presented below is only for participants included in the actual analysis.

The MCS ranges from 0 to 12 and is a composite of 4 assessments (each rated from 0-3): stool frequency, rectal bleeding, endoscopy, and physician's global assessment. Higher scores represent greater disease severity. Remission was defined as MCS less than or equal to (≤)2 with individual subscores ≤1 and a rectal bleeding subscore of 0. Clinical Remission is MCS ≤2 with individual subscores ≤1.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in the maintenance phase who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation. Data presented below is only for participants included in the actual analysis.

The MCS ranges from 0 to 12 and is a composite of 4 assessments (each rated from 0-3): stool frequency, rectal bleeding, endoscopy, and physician's global assessment. Higher scores represent greater disease severity. Remission was defined as MCS less than or equal to (≤)2 with individual subscores ≤1 and a rectal bleeding subscore of 0. Clinical Remission is MCS ≤2 with individual subscores ≤1.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in the maintenance phase who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation.

The MCS ranges from 0 to 12 and is a composite of 4 assessments (each rated from 0-3): stool frequency, rectal bleeding, endoscopy, and physician's global assessment. Higher scores represent greater disease severity. Remission was defined as MCS less than or equal to (≤)2 with individual subscores ≤1 and a rectal bleeding subscore of 0.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in the maintenance phase who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation. Data presented below is only for participants included in the actual analysis.

The MCS ranges from 0 to 12 and is a composite of 4 assessments (each rated from 0-3): stool frequency, rectal bleeding, endoscopy, and physician's global assessment. Higher scores represent greater disease severity. Improvement in endoscopic appearance of the mucosa is Endoscopy subscore ≤1.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in the maintenance phase who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation.

Nancy Histological Index (NHI) is a 5-level classification ranging from grade 0 (No histologically significant disease) to grade 4 (severely active disease). Histologic remission is defined as a Nancy Histological Index of 0 or 1.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in the maintenance phase who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation. Data presented below is only for participants included in the actual analysis.

The MCS ranges from 0 to 12 and is a composite of 4 assessments (each rated from 0-3): stool frequency, rectal bleeding, endoscopy, and physician's global assessment. Higher scores represent greater disease severity. Endoscopic Remission is Endoscopy subscore = 0.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in the maintenance phase who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation.

The MCS ranges from 0 to 12 and is a composite of 4 assessments (each rated from 0-3): stool frequency, rectal bleeding, endoscopy, and physician's global assessment. Higher scores represent greater disease severity. Corticosteroid-Free analysis was conducted only on a subgroup of participants who were randomized into the maintenance phase and receiving Corticosteroids (CS) at baseline. Participants were defined as being off CS if they had no record of taking CS on the date that was 24 weeks prior to Week 66.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in the maintenance phase who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation. Data presented below is only for participants included in the actual analysis.

The MCS ranges from 0 to 12 and is a composite of 4 assessments (each rated from 0-3): stool frequency, rectal bleeding, endoscopy, and physician's global assessment. Higher scores represent greater disease severity. Corticosteroid-Free analysis was conducted only on a subgroup of participants who were randomized into the maintenance phase and receiving Corticosteroids (CS) at baseline. Participants were defined as being off CS if they had no record of taking CS on the date that was 24 weeks prior to Week 66.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in the maintenance phase who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation. Data presented below is only for participants included in the actual analysis.

The UC-PRO questionnaire is collected in the e-diary and completed by participants for at least 9-12 consecutive days prior to a study visit. The UC-PRO is being reported in three domains; two domains are key endpoints and reported as UC-PRO Signs and Symptoms (UC-PRO/SS). The bowel domain score ranges from 0-27, with a higher score indicating a worse disease state.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in the maintenance phase who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation. Data presented below is only for participants included in the actual analysis.

The UC-PRO questionnaire is collected in the e-diary and completed by participants for at least 9-12 consecutive days prior to a study visit. The UC-PRO is being reported in three domains; two domains are key endpoints and reported as UC-PRO Signs and Symptoms (UC-PRO/SS). The functional (abdominal symptoms) domain score ranges from 0-12, with a higher score indicating a worse disease state.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in the maintenance phase who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation. Data presented below is only for participants included in the actual analysis.

The IBDQ is used to assess participant's health-related quality of life (QOL). The IBDQ score is a Total Score summed up from across all 32 questions on the questionnaire. The Total Score range is from 32 to 224 with higher scores representing a better quality of life.

The Modified Intent-to-Treat (mITT) population was defined as all participants randomised in the maintenance phase who received at least one dose of study drug, with participants grouped according to the treatment assigned at randomisation. Data presented below is only for participants included in the actual analysis.

All Adverse Events (AEs) were graded for severity using the NCI-CTCAE v4.0. Any AE not specifically listed was assessed per the following 5 grades: Grade 1 = mild; asymptomatic or mild symptoms; clinical or diagnostic observations only; or intervention not indicated. Grade 2 = moderate; minimal, local, or non-invasive intervention indicated; or limiting age-appropriate instrumental activities of daily living. Grade 3 = severe or medically significant, but not immediately life-threatening; hospitalization or prolongation of hospitalization indicated; disabling; or limiting self-care activities of daily living. Grade 4 = life-threatening consequences or urgent intervention indicated. Grade 5 = death related to AE. Not all grades are appropriate for all AEs; some AEs have fewer than 5 options. The terms "severe" and "serious" are not synonymous and are independently assessed for each AE. Multiple occurrences of AEs were counted only once per participant at the highest (worst) grade.

The Safety Population was defined as all participants who received at least one dose of study drug during the induction and maintenance phases. Participants were grouped by cohort and included in the treatment arm for the treatment most frequently received during the induction and maintenance phases.

The Safety Population was defined as all participants who received at least one dose of study drug during the induction and maintenance phases. Participants were grouped by cohort and included in the treatment arm for the treatment most frequently received during the induction and maintenance phases.

The Safety Population was defined as all participants who received at least one dose of study drug during the induction and maintenance phases. Participants were grouped by cohort and included in the treatment arm for the treatment most frequently received during the induction and maintenance phases.

All Adverse Events (AEs) were graded for severity using the NCI-CTCAE v4.0. Any AE not specifically listed was assessed per the following 5 grades: Grade 1 = mild; asymptomatic or mild symptoms; clinical or diagnostic observations only; or intervention not indicated. Grade 2 = moderate; minimal, local, or non-invasive intervention indicated; or limiting age-appropriate instrumental activities of daily living. Grade 3 = severe or medically significant, but not immediately life-threatening; hospitalization or prolongation of hospitalization indicated; disabling; or limiting self-care activities of daily living. Grade 4 = life-threatening consequences or urgent intervention indicated. Not all grades are appropriate for all AEs; some AEs have fewer than 5 options. The terms "severe" and "serious" are not synonymous and are independently assessed for each AE. Multiple occurrences of AEs were counted only once per participant at the highest (worst) grade.

The Safety Population was defined as all participants who received at least one dose of study drug during the induction and maintenance phases. Participants were grouped by cohort and included in the treatment arm for the treatment most frequently received during the induction and maintenance phases.

The Safety Population was defined as all participants who received at least one dose of study drug during the induction and maintenance phases. Participants were grouped by cohort and included in the treatment arm for the treatment most frequently received during the induction and maintenance phases.

The Safety Population was defined as all participants who received at least one dose of study drug during the induction and maintenance phases. Participants were grouped by cohort and included in the treatment arm for the treatment most frequently received during the induction and maintenance phases.

The Safety Population was defined as all participants who received at least one dose of study drug during the induction and maintenance phases. Participants were grouped by cohort and included in the treatment arm for the treatment most frequently received during the induction and maintenance phases.

A tiered strategy was used to detect and characterize etrolizumab antibodies within this clinical study. When determining post baseline incidence, participants were considered to be ADA positive if they were ADA negative or had missing data at baseline but developed an ADA response following etrolizumab drug exposure (treatment-induced ADA response), or if they were ADA positive at baseline and the titer of one or more post baseline samples was at least 0.60 titer unit greater than the titer of the baseline sample (treatment-enhanced ADA response). Participants were considered to be ADA negative if they were ADA negative or had missing data at baseline and all post baseline samples were negative, or if they were ADA positive at baseline but did not have any post baseline samples with a titer that was at least 0.60 titer unit greater than the titer of the baseline sample (treatment unaffected).

Participants who received at least one dose of study treatment and had at least one baseline or post-baseline ATA result from at least one sample. For the Induction Phase, data for Cohorts 1 and 2 are combined to present the Etrolizumab Induction data for participants not randomised into the Maintenance phase.

As per Protocol, the timepoints for each arm where more than a third of the samples were above the lower limit of quantification (LLOQ), full summary statistics (Mean and Standard Deviation) were reported. For timepoints below the LLOQ, only the Median and Max were reported as a separate outcome measure below.

All participants who received at least one dose of study drug and had evaluable PK data. For the Induction Phase, data for Cohorts 1 and 2 are combined to present the Etrolizumab Induction data for participants not randomised into the Maintenance phase.

As per Protocol, the timepoints for each arm where more than a third of the samples were below the LLOQ only the Median and Max were reported.

All participants who received at least one dose of study drug and had evaluable PK data and were part of the timepoints that had more than a third of samples below LLOQ. For the Induction Phase, data for Cohorts 1 and 2 are combined to present the Etrolizumab Induction data for participants not randomised into the Maintenance phase.