Clinically significant exacerbation is defined as worsening of asthma which requires use of systemic corticosteroids and/or hospitalizations and/or Emergency Department (ED) visits. Analysis of the number of exacerbations was performed using a negative binomial model with covariates of treatment group, baseline maintenance Oral Corticosteroids (OCS) therapy (OCS vs. no OCS), region, exacerbations in the year prior to the study (as an ordinal variable) and baseline % predicted Forced Expiratory Volume in 1 second (FEV1), and with logarithm of time on treatment as an offset variable.

The analysis was performed on the Modified Intent-to-Treat (MITT) Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded.

Clinically significant exacerbation is defined as worsening of asthma which requires use of systemic corticosteroids and/or hospitalizations and/or Emergency Department (ED) visits. Analysis of the number of exacerbations was performed using a negative binomial model with covariates of treatment group, baseline maintenance Oral Corticosteroids (OCS) therapy (OCS vs. no OCS), region, exacerbations in the year prior to the study (as an ordinal variable) and baseline % predicted Forced Expiratory Volume in 1 second (FEV1), and with logarithm of time on treatment as an offset variable. Time to first clinically significant exacerbation was analyzed using Kaplan-Meier estimates and expressed in terms of probability.

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded.

The SGRQ Questionnaire is a well-established, self-completed tool, with 50 questions comprising three domains: Symptoms, Activity, and Impacts scores (each ranging from 0 to 100; where higher score indicates worst outcome). SGRQ total score was calculated by summing weights from all positive items, divided by sum of weights for all items in SGRQ questionnaire and multiplying by 100. The SGRQ total score ranges from 0 to 100, with 0 implying the best possible health status and 100 implying worst possible health status. Analysis was performed using mixed model repeated measures with covariates of baseline, baseline maintenance OCS therapy (OCS vs. no OCS), exacerbations in the year prior to the study (as an ordinal variable), baseline % predicted FEV1, treatment and visit, plus interaction terms for visit by baseline and visit by treatment group.

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded. Number of participants analyzed signifies those participants who were evaluable for this outcome measure.

An exacerbation is defined as worsening of asthma requiring the use of systemic corticosteroids and/or emergency department visit, or hospitalization. The number of exacerbations requiring hospitalization including incubation and admittance to an Intensive care unit (ICU) or ED visits were evaluated. Analysis of number of exacerbations was performed using a negative binomial model with covariates of treatment group, baseline maintenance OCS therapy (OCS vs. no OCS), exacerbations in the year prior to the study (as an ordinal variable) and baseline % predicted FEV1, and with logarithm of time on treatment as an offset variable. The data for participants with 0, 1, 2 and 3 exacerbations requiring hospitalization (including intubation and admittance to an ICU) or ED visits are summarized.

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded.

An exacerbation is defined as worsening of asthma requiring the use of systemic corticosteroids and/or emergency department visit, or hospitalization. Analysis of number of exacerbations was performed using a negative binomial model with covariates of treatment group, baseline maintenance OCS therapy (OCS vs. no OCS), exacerbations in the year prior to the study (as an ordinal variable) and baseline % predicted FEV1, and with logarithm of time on treatment as an offset variable. The summary data for participants with 0, 1, 2 and 3 exacerbations requiring hospitalization are summarized.

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded.

FEV1 is the volume of air that can be forced out in one second after taking a deep breath. Prebronchodilator FEV1 were measured via spirometer at Baseline and Week 52. Analysis was performed using mixed model repeated measures with covariates of baseline, baseline maintenance OCS therapy (OCS vs. no OCS), exacerbations in the year prior to the study (as an ordinal variable), treatment and visit, plus interaction terms for visit by baseline and visit by treatment group.

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded. Number of participants analyzed signifies those participants who were evaluable for this outcome measure.

AE is any untoward medical occurrence in a participant or clinical investigation participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. Systemic reactions and local injection site reactions are adverse events of special interest (AESIs).

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded.

Blood samples was collected for the assessment of change from baseline in hematology parameter Platelets count. Baseline was defined as the latest pre-dose assessment with a non-missing value, including those from unscheduled visits. Change from Baseline was calculated by subtracting the post dose visit value from the Baseline value.

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded. Number of participants analyzed signifies those participants who were evaluable for this outcome measure.

Blood samples was collected for the assessment of change from baseline in hematology parameter Erythrocytes count. Baseline was defined as the latest pre-dose assessment with a non-missing value, including those from unscheduled visits. Change from Baseline was calculated by subtracting the post dose visit value from the Baseline value.

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded. Number of participants analyzed signifies those participants who were evaluable for this outcome measure.

Blood samples was collected for the assessment of change from baseline in hematology parameter Hematocrit. Baseline was defined as the latest pre-dose assessment with a non-missing value, including those from unscheduled visits. Change from Baseline was calculated by subtracting the post dose visit value from the Baseline value.

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded. Number of participants analyzed signifies those participants who were evaluable for this outcome measure.

Blood samples was collected for the assessment of change from baseline in WBC) count with differential (neutrophils, lymphocytes, monocytes. eosinophils and basophils). Baseline was defined as the latest pre-dose assessment with a non-missing value, including those from unscheduled visits.

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded. Number of participants analyzed signifies those participants who were evaluable for this outcome measure.

Blood samples was collected for the assessment of change from baseline in clinical parameter Alkaline Phosphatase. Baseline was defined as the latest pre-dose assessment with a non-missing value, including those from unscheduled visits. Change from Baseline was calculated by subtracting the post dose visit value from the Baseline value.

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded. Number of participants analyzed signifies those participants who were evaluable for this outcome measure.

Blood samples was collected for the assessment of change from baseline in clinical parameter Alanine Aminotransferase, Aspartate Aminotransferase. Baseline was defined as the latest pre-dose assessment with a non-missing value, including those from unscheduled visits. Change from Baseline was calculated by subtracting the post dose visit value from the Baseline value.

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded. Number of participants analyzed signifies those participants who were evaluable for this outcome measure.

Blood samples was collected for the assessment of change from baseline in clinical parameter albumin, total protein. Baseline was defined as the latest pre-dose assessment with a non-missing value, including those from unscheduled visits. Change from Baseline was calculated by subtracting the post dose visit value from the Baseline value.

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded. Number of participants analyzed signifies those participants who were evaluable for this outcome measure.

Blood samples was collected for the assessment of change from baseline in clinical parameter including total and direct bilirubin, creatinine, glucose, calcium, sodium, potassium, urea. Baseline was defined as the latest pre-dose assessment with a non-missing value, including those from unscheduled visits. Change from Baseline was calculated by subtracting the post dose visit value from the Baseline value.

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded. Number of participants analyzed signifies those participants who were evaluable for this outcome measure. Here 'number analyzed' signifies those participants who were evaluated at specified category.

SBP and DBP were measured in a sitting position after 5 minutes rest. The normal range for SBP is 90-140 mmHg and DBP is 60-90 millimeters of mercury (mmHg).

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded. Number of participants analyzed signifies those participants who were evaluable for this outcome measure.

Pulse rate measurement were measured in a sitting position after 5 minutes rest.

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded. Number of participants analyzed signifies those participants who were evaluable for this outcome measure.

12-Lead electrocardiogram (ECG) measurements were obtained after the participants had rested in the supine position for 5 minutes. Clinically significant abnormal findings are based on the judgement of the investigator.

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded. Number of participants analyzed signifies those participants who were evaluable for this outcome measure.

Blood samples were collected for detection of binding and neutralizing anti-mepolizumab antibodies. Samples with a positive screening result continued for confirmation analysis. Samples with a positive confirmation analysis were considered positive for mepolizumab Anti-drug antibody (ADA).

The analysis was performed on the MITT Set that included all randomized participants who received at least one dose of trial medication. 'Modified' implies that participants who were randomized but did not receive study treatment were excluded.