AE defined as any untoward medical occurrence in clinical investigation participants administered drug; it does not necessarily have to have causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (example, a clinically significant abnormal laboratory finding), symptom, or disease temporally associated with the use of a drug whether or not it was considered related to the drug. TEAE was defined as an AE whose date of onset occurred on or after the first dose of study drug, or an already-present AE that worsened in intensity or frequency following the treatment start, occurring from the first dose of study drug to the day of last dose of study drug.

Safety Analysis Set (SAS). As prespecified in the SAP, safety data were pooled and summarized based on the last actual treatment regimen received during the study, accounting for dose escalation. Participants were assigned to treatment groups UC and CD according to the highest dose received (300 mg) at Week 40. The 300 mg (escalated dose) group therefore included participants who had previously received 100 mg, 150 mg, and/or 200 mg during the study.

Clinical response was defined as a continued reduction in complete Mayo score of >=3 points and >=30 percent (%) from baseline (at initiation of MLN0002-2003) and continued decrease in rectal bleeding subscore of >=1 point from baseline, or absolute rectal bleeding subscore of less than or equal to (<=1) point. Mayo score was an instrument designed to measure disease activity of UC. It consisted of 4 subscores: stool frequency, rectal bleeding, findings on endoscopy and physician rating of disease activity, each graded from 0 to 3 where 0 indicated normal and 3 indicated more severe disease. These scores were summed to give a total score range of 0 to 12; where higher scores indicated more severe disease.

Modified Week 32 analysis set included participants who had consented under Protocol Amendment (PA) 5 before their Week 32 visit, or (b) had not consented under PA 5 before their Week 32 visit and had completed an optional diary for Week 32, or (c) had not consented under PA 5 and had discontinued before Week 32. Here, "Overall Number of Participants Analyzed signifies the participants who were evaluable for this outcome measure.

Maintenance of clinical response based on SES-CD and CDAI was defined as a 50% reduction in SES-CD score on endoscopy compared to the baseline endoscopy [at initiation of MLN0002-2003 (NCT03138655)]; and continued reduction in CDAI that is a >= 70 point decrease from the baseline CDAI score at the initiation of MLN0002-2003 (NCT03138655). CDAI was a research tool used to quantify the symptoms of participants with Crohn's disease. SES-CD consisted of 3 variables: ulcer size, ulcerated and affected surfaces and presence of narrowing each graded from 0 to 3 with score of 0 means no colonic lesions or mucosal healing, and SES-CD greater than (>) 1 indicated the presence of mucosal lesions.

Modified Week 32 analysis set included participants who had consented under PA 5 before their Week 32 visit, or (b) had not consented under PA 5 before their Week 32 visit and had completed an optional diary for Week 32, or (c) had not consented under PA 5 and had discontinued before Week 32. Here, "Overall Number of Participants Analyzed" signifies the participants who were evaluable for this outcome measure.

Time to major IBD-related events was defined as time from study treatment start to first major IBD-related hospitalization, surgery, or procedure due to UC and CD.

FAS included all enrolled participants who received at least one dose of study drug.

The IMPACT-III questionnaire was a self-reported measure with 35 closed questions encompassing 6 domains: Bowel Symptoms (7 items), Systemic Symptoms (3 items), Social Functioning (12 items), Body Image (3 items), Treatment/Interventions (3 items), and Emotional Functioning (7 items). The IMPACT-III used a 5-point Likert scale ranging from 1 to 5 for all answers. The total score was obtained by summing individual domain scores. The total score ranged from 35 to 175, with higher scores suggesting better quality of life.

FAS included all enrolled participants who received at least one dose of study drug in study. Here "Overall Number of Participants Analyzed" signifies participants who were evaluable for this outcome measure and "number analyzed" signifies participants in the specific timepoints. No participants were analyzed or reported in the UC Participants (<30 kg): Vedolizumab 100 mg treatment arm, as no participants had baseline assessments. Therefore, change-from-baseline could not be derived.

The IMPACT-III questionnaire was a self-reported measure with 35 closed questions encompassing 6 domains. The Bowel Symptoms domain consisted of 7 items. Each item was scored using a 5-point Likert scale ranging from 1 to 5. The bowel symptoms domain score ranged from 7 to 35, with higher scores suggesting a better quality of life.

FAS included all enrolled participants who received at least one dose of study drug in study. Here "Overall Number of Participants Analyzed" signifies participants who were evaluable for this outcome measure and "number analyzed" signifies participants in the specific timepoints. No participants were analyzed or reported in the UC Participants (<30 kg): Vedolizumab 100 mg treatment arm, as no participants had baseline assessments. Therefore, change-from-baseline could not be derived.

The IMPACT-III questionnaire was a self-reported measure with 35 closed questions encompassing 6 domains. The systemic symptoms domain consisted of 3 items. Each item was scored using a 5-point Likert scale ranging from 1 to 5. The systemic symptoms domain score ranged from 3 to 15, with higher scores suggesting a better quality of life.

FAS included all enrolled participants who received at least one dose of study drug in study. Here "Overall Number of Participants Analyzed" signifies participants who were evaluable for this outcome measure and "number analyzed" signifies participants in the specific timepoints. No participants were analyzed or reported in the UC Participants (<30 kg): Vedolizumab 100 mg treatment arm, as no participants had baseline assessments. Therefore, change-from-baseline could not be derived.

The IMPACT-III questionnaire was a self-reported measure with 35 closed questions encompassing 6 domains. The social functioning domain consisted of 12 items. Each item was scored using a 5-point Likert scale ranging from 1 to 5. The social functioning domain score ranged from 12 to 60, with higher scores suggesting a better quality of life.

FAS included all enrolled participants who received at least one dose of study drug in study. Here "Overall Number of Participants Analyzed" signifies participants who were evaluable for this outcome measure and "number analyzed" signifies participants in the specific timepoints. No participants were analyzed or reported in the UC Participants (<30 kg): Vedolizumab 100 mg treatment arm, as no participants had baseline assessments. Therefore, change-from-baseline could not be derived.

The IMPACT-III questionnaire was a self-reported measure with 35 closed questions encompassing 6 domains. The body image domain consisted of 3 items. Each item was scored using a 5-point Likert scale ranging from 1 to 5. The body image domain score ranged from 3 to 15, with higher scores suggesting a better quality of life.

FAS included all enrolled participants who received at least one dose of study drug in study. Here "Overall Number of Participants Analyzed" signifies participants who were evaluable for this outcome measure and "number analyzed" signifies participants in the specific timepoints. No participants were analyzed or reported in the UC Participants (<30 kg): Vedolizumab 100 mg treatment arm, as no participants had baseline assessments. Therefore, change-from-baseline could not be derived.

The IMPACT-III questionnaire was a self-reported measure with 35 closed questions encompassing 6 domains. The treatment/interventions domain consisted of 3 items. Each item was scored using a 5-point Likert scale ranging from 1 to 5. The treatment/interventions domain score ranged from 3 to 15, with higher scores suggesting a better quality of life.

FAS included all enrolled participants who received at least one dose of study drug in study. Here "Overall Number of Participants Analyzed" signifies participants who were evaluable for this outcome measure and "number analyzed" signifies participants in the specific timepoints. No participants were analyzed or reported in the UC Participants (<30 kg): Vedolizumab 100 mg treatment arm, as no participants had baseline assessments. Therefore, change-from-baseline could not be derived.

The IMPACT-III questionnaire was a self-reported measure with 35 closed questions encompassing 6 domains. The emotional functioning domain consisted of 7 items. Each item was scored using a 5-point Likert scale ranging from 1 to 5. The emotional functioning domain score ranged from 7 to 35, with higher scores suggesting a better quality of life.

FAS included all enrolled participants who received at least one dose of study drug in study. Here "Overall Number of Participants Analyzed" signifies participants who were evaluable for this outcome measure and "number analyzed" signifies participants in the specific timepoints. No participants were analyzed or reported in the UC Participants (<30 kg): Vedolizumab 100 mg treatment arm, as no participants had baseline assessments. Therefore, change-from-baseline could not be derived.

Height velocity (centimeter per year [cm/year]) was calculated as the change in height divided by the duration [time between the two height measures].

FAS included all enrolled participants who received at least one dose of study drug. Here, "Overall Number of Participants Analyzed" signifies participants who were evaluable for this outcome measure and "number analyzed" signifies participants in the specific categories.

Change from baseline in height was reported.

FAS included all enrolled participants who received at least one dose of study drug. Here, "Overall Number of Participants Analyzed" signifies participants who were evaluable for this outcome measure and "number analyzed" signifies participants in the specific categories.

Change from baseline in weight was reported.

FAS included all enrolled participants who received at least one dose of study drug. Here, "Overall Number of Participants Analyzed" signifies participants who were evaluable for this outcome measure and "number analyzed" signifies participants in the specific categories.

BMI was calculated as Weight (in kilograms)/height (in meters square).

FAS included all enrolled participants who received at least one dose of study drug in study. Here, "Overall Number of Participants Analyzed" signifies participants who were evaluable for this outcome measure and "number analyzed" signifies participants in the specific categories.

Tanner Stage Evaluation was a scale used to evaluate growth parameters standardized for age, sex, and pubertal development. Female pubertal development staged by pubic hair development and breast size; male pubertal development staged by size of the genitalia and development of pubic hair. Rated in 5 stages: stage 1 (no development) to 5 (adult-like development in quantity and size). Tanner stage was assessed at or before age 16 years for females or 17 years for males.

FAS included all enrolled participants who received at least one dose of study drug in study. Here, "Overall Number of Participants Analyzed" signifies participants who were evaluable for this outcome measure and "number analyzed" signifies participants in the specific categories.