Pharmacokinetics and Pharmacodynamics of Mepolizumab Administered Subcutaneously in Children

Study Overview
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Brief Summary
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Mepolizumab is a humanized immunoglobulin G (IgG1) monoclonal antibody (mAb) that exhibits dose proportional and time-independent pharmacokinetics. The study will be conducted in 2 parts. Part A: it will be pharmacokinetic (PK) and pharmacodynamic (PD) study conducted to support the use of mepolizumab in children aged 6 to 11 years with severe eosinophilic asthma and characterize the PK/PD of mepolizumab 40 milligrams (mg) or 100 mg administered subcutaneously depending on participant body weight. Part B: It is a long-term safety / pharmacodynamic phase in which extended treatment for a further 52 weeks will be offered on an optional basis to those subjects eligible for continued treatment. Participants with bodyweight <40 kilogram (kg) will be dosed with mepolizumab 40 mg and participants with body weight >=40 kg will be dosed with mepolizumab 100 mg subcutaneously in upper arm or thigh at Visit 2 (Week 0). Approximately 40 male or female participants aged 6 to 11 years will be screened to achieve approximately 28 eligible participants entering the treatment phase to allow availability of 20 evaluable participants, with a minimum of six participants enrolled in the <40 kg bodyweight group. The total duration of the study will be 22 weeks and will include a run-in period of 1-2 weeks, a treatment period of 12 weeks and a follow-up phase of 8 weeks. A participant will be considered having completed the study if the participant completes all phases of the study including the follow-up phase (Week 20 [visit 8]).

Official Title
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An Open-label Study to Characterize the Pharmacokinetics and Pharmacodynamics of Mepolizumab Administered Subcutaneously in Children From 6 to 11 Years of Age With Severe Eosinophilic Asthma

Conditions
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Asthma

Intervention / Treatment
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* Drug: Mepolizumab


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Between 6 and 11 years of age inclusive, at the time of screening. Diagnosis of severe asthma, defined by the regional asthma guidelines (i.e., National Institute of Health (NIH), Global Initiative for Asthma (GINA), etc.), for at least 12 months prior to Visit 1. If the participant is naïve to the study site, the participant/guardian must self-report a physician diagnosis of asthma and the investigator must confirm by review of medical history with the participant/guardian. Eosinophilic airway inflammation that is related to asthma characterized as eosinophilic in nature as indicated by: elevated peripheral blood eosinophil count of >=300 cells per microliter (cells/μL) demonstrated in the past 12 months OR elevated peripheral blood eosinophil count of >=150/μL at visit 1. A well-documented requirement for regular treatment with inhaled corticosteroid (>200 μg/day fluticasone propionate drug powder inhaler [DPI] or equivalent daily) in the 12 months prior to Visit 1 with or without maintenance oral corticosteroids (OCS). The ICS dose should represent medium or high dose in children aged 6-11 years of age [GINA, 2015]. Current treatment with an additional controller medication for at least 3 months or a documented failure in the past 12 months of an additional controller medication for at least 3 successive months. [e.g., long-acting beta-2-agonist (LABA), leukotriene receptor antagonist (LTRA), or theophylline.] Forced expiratory volume in one second (FEV1): Persistent airflow obstruction at either Visit 1 or Visit 2 (FEV1 performed prior to first dose of study medication) as indicated by: A pre-bronchodilator FEV1 <110% predicted (Quanjer, 2012) OR FEV1: Forced vital capacity (FVC) ratio <0.8. Previously confirmed history of two or more exacerbations requiring treatment with systemic corticosteroids (CS) (intramuscular [IM], intravenous, or oral), in the 12 months prior to visit 1, despite the use of high-dose inhaled corticosteroids (ICS). For participants receiving maintenance CS, the CS treatment for the exacerbations must have been a two-fold increase or greater in the dose. No changes in the dose or regimen of baseline ICS and/or additional controller medication during the run-in period. Male or female: Females of childbearing potential must commit to consistent and correct use of an acceptable method of contraception for the duration of the trial and for 4 months after the last dose of investigational product. A urine pregnancy test is required of girls of childbearing potential. This test will be performed at the initial screening visit (visit 1) and will be performed at each scheduled study visit prior to the administration of investigational product, and during the early withdrawal and follow-up visits. Parent(s)/guardian able to give written informed consent prior to participation in the study, which will include the ability to comply with the requirements and restrictions listed in the consent form. If applicable, the participant must be able and willing to give assent to take part in the study according to the local requirement. For Part B: The subject has completed all study assessments up-to and including Visit 8 and received all 3 doses of investigational product (IP) in Part A For Part B: The Principal Investigator (PI) has performed a benefit/risk assessment and this assessment supports continued therapy with mepolizumab. The subject's parents (or guardian) have given consent and the subject has given assent for continued treatment Exclusion Criteria: Participants with any history of life threatening asthma (e.g. requiring intubation), immunosuppressive medications intake or immunodeficiency disorder. Participants with any medical condition or circumstance making the volunteer unsuitable for participation in the study. Significant abnormality of rate, interval, conduction or rhythm in the 12-lead electrocardiogram (ECG), determined by the investigator in conjunction with the age and gender of the child at Visit 1. Alanine aminotransferase (ALT), and bilirubin >2x upper limit of normal (ULN) (isolated bilirubin >1.5xULN is acceptable if bilirubin is fractionated and direct bilirubin <35%) at Visit 1. Positive Hepatitis B Surface Antigen or positive Hepatitis C antibody at Visit 1. Parent/guardian has a history of psychiatric disease, intellectual deficiency, substance abuse, or other condition (e.g. inability to read, comprehend and write) which will limit the validity of consent to participate in this study. Unwillingness or inability of the participant or parent/guardian to follow the procedures outlined in the protocol. Participant who is mentally or legally incapacitated. Children who are wards of the state or government. A participant will not be eligible for this study if he/she is an immediate family member of the participating investigator, sub-investigator, study coordinator, or employee of the participating investigator. Omalizumab: Participants who have received omalizumab within 130 days of Visit 1. Other Biologics: Participants who have received any biological (other than omalizumab) to treat inflammatory disease within 5 half-lives of visit 1. History of sensitivity to any of the study medications, or components thereof or a history of drug or other allergy that, in the opinion of the investigator or Medical Monitor, contraindicates their participation. Hypersensitivity: Participants with allergy/intolerance to a monoclonal antibody or biologic. The participant has participated in a clinical trial and has received an investigational product within the following time period prior to the first dosing day in the current study: 30 days, 5 half-lives or twice the duration of the biological effect of the investigational product (whichever is longer).

Ages Eligible for Study
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Minimum Age: 6 Years
Maximum Age: 11 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Mepolizumab 40 mg in Part A and B<br>Participants with bodyweight < 40 kg will receive 0.4 milliliter (mL) of reconstituted mepolizumab subcutaneously, in upper arm or thigh. | Drug: Mepolizumab<br>* Mepolizumab is supplied as 100 mg lyophilised cake in sterile vials for subcutaneous administration in upper arm or thigh. The vial will be reconstituted with sterile water for injection prior to individual use.<br>|
| Experimental: Mepolizumab 100 mg in Part A and B<br>Participants with bodyweight >= 40 kg will receive 1.0 mL of reconstituted mepolizumab subcutaneously, in upper arm or thigh. | Drug: Mepolizumab<br>* Mepolizumab is supplied as 100 mg lyophilised cake in sterile vials for subcutaneous administration in upper arm or thigh. The vial will be reconstituted with sterile water for injection prior to individual use.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Maximum Plasma Concentration (Cmax) of Mepolizumab for Part A | PK of mepolizumab was evaluated in participants using Cmax. PK samples were collected at pre-dose on Weeks 4 and 8; and at Weeks 9, 12, 16 and 20 post-dose. Cmax was evaluated by population PK methods and mean and standard error from the final model has been tabulated. Estimates have been presented from the final model centered to mean bodyweights of 27 kg, 50 kg and 70 kg. Note the average bodyweight of 70 kg (mean body weight observed in adults) was not investigated in the study. PK Population included all participants receiving at least one dose of mepolizumab beginning at Visit 2 (Week 0) and having at least one blood sample taken at Visit 3 (Week 4) or thereafter with measurable mepolizumab plasma concentration. | Pre-dose on Weeks 4 and 8; Weeks 9, 12, 16 and 20 post-dose | 
| Area Under Concentration Time Curve to Infinity (AUC [0-inf]) of Mepolizumab for Part A | PK of mepolizumab was evaluated in participants using AUC (0-inf). PK samples were collected at pre-dose on Weeks 4 and 8; and at Weeks 9, 12, 16 and 20 post-dose. AUC (0-inf) was evaluated by population PK methods and mean and standard error from the final model has been tabulated. Estimates have been presented from the final model centered to mean bodyweights of 27 kg, 50 kg and 70 kg. Note the average bodyweight of 70kg (mean body weight observed in adults) was not investigated in the study. | Pre-dose on Weeks 4 and 8; Weeks 9, 12, 16 and 20 post-dose | 
| Terminal Phase Elimination Half-life (T1/2) of Mepolizumab During Treatment Period for Part A | PK of mepolizumab was evaluated in participants using t1/2. PK samples were collected at pre-dose on Weeks 4 and 8; and at Weeks 9, 12, 16 and 20 post-dose. T1/2 was evaluated by population PK methods and mean and standard error from the final model has been tabulated. Estimates have been presented from the final model centered to mean bodyweights of 27 kg, 50 kg and 70 kg. Note the average bodyweight of 70kg (mean body weight observed in adults) was not investigated in the study. | Pre-dose on Weeks 4 and 8; Weeks 9, 12, 16 and 20 post-dose | 
| Plasma Apparent Clearance (CL/F) of Mepolizumab in Part A | PK of mepolizumab was evaluated in participants using CL/F. PK samples were collected at pre-dose on Weeks 4 and 8; and at Weeks 9, 12, 16 and 20 post-dose. CL was evaluated by population PK methods and mean and standard error from the final model has been tabulated. Estimates have been presented from the final model centered to mean bodyweights of 27 kg, 50 kg and 70 kg. Note the average bodyweight of 70kg (mean body weight observed in adults) was not investigated in the study. | Pre-dose on Weeks 4 and 8; Weeks 9, 12, 16 and 20 post-dose | 
| Ratio to Baseline in Absolute Blood Eosinophil Count at Week 12 for Part A | PD of mepolizumab was evaluated in participants using ratio to Baseline in absolute blood eosinophil count. Blood samples were collected at indicated time points. Baseline was defined as the latest value recorded prior to the first dose of mepolizumab. Ratio to Baseline was calculated as post-dose visit value/Baseline value. It was evaluated by Pharmacodynamic Eosinophils (PDe) Population which included all participants receiving at least one dose of mepolizumab beginning at Visit 2 (Week 0) and having at least one Part A blood sample evaluable for blood eosinophil count. | Baseline and Week 12 | 
| Number of Participants With on Treatment Serious Adverse Events (SAEs) and Non-SAEs for Part B | An 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. Any untoward event resulting in death, life threatening, requires hospitalization or prolongation of existing hospitalization, results in disability/incapacity, congenital anomaly/birth defect, any other situation according to medical or scientific judgment or all events of possible drug-induced liver injury with hyperbilirubinemia are to be categorized as SAE. On-treatment SAEs and non-SAEs are defined as events occurring from the first Part B dose until 28 days following the last Part B dose. Safety Population includes all participants who received at least one dose of mepolizumab beginning at Visit 9. | From Week 20 and up to Week 72 | 
| Number of Participants With Positive Anti-mepolizumab Binding Antibodies and Neutralizing Antibodies Response for Part B | Blood sample were collected for the determination of anti-mepolizumab binding antibodies and neutralizing antibodies response in Part B at Weeks 44, 68 and 80 prior to study treatment administration. Participant was considered 'Positive' if they had at least one positive post-Baseline anti-drug antibody assay result. All Part B visits (including scheduled and unscheduled) post-Baseline were considered for Any-time Post-Baseline visit derivation. The number of participants with positive anti-mepolizumab binding antibodies and neutralizing antibodies response at Any Time Post Baseline has been presented. The neutralizing antibodies response results only presented for participants with positive anti-drug antibody assay. | From Week 20 and up to Week 80 | 
| Change From Baseline in Sitting Systolic Blood Pressure (SBP) and Diastolic Blood Pressure (DBP) for Part B | Sitting blood pressure measurements included SBP and DBP. Measurements were done pre-infusion/injection with the participant sitting, having rested in this position for at least 5 minutes before each reading. The Baseline was defined as the latest value recorded prior to the first dose of mepolizumab. Change from Baseline was defined as value at indicated time point minus Baseline value. Only those participants with data available at the specified time points were analyzed (represented by n=X in the category titles). | Baseline and Weeks 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72, 80 | 
| Change From Baseline in Sitting Pulse Rate for Part B | Sitting pulse rate measurements were performed pre-infusion/injection with the participant sitting, having rested in this position for at least 5 minutes before each reading. The Baseline was defined as the latest value recorded prior to the first dose of mepolizumab in Part A. Change from Baseline was defined as value at indicated time point minus Baseline value. Only those participants with data available at the specified time points were analyzed (represented by n=X in the category titles). | Baseline and Weeks 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72, 80 | 
| Number of Participants With Any Time Change From Baseline Relative to Normal Range in Clinical Chemistry Parameters for Part B | Blood samples were collected for analysis of alanine aminotransferase (ALT), alkaline phosphatase (ALP), aspartate aminotransferase (AST), gamma glutamyl transferase (GGT), albumin, protein, bilirubin, creatinine, urate, direct bilirubin, calcium, carbon dioxide (CO2), chloride, glucose, potassium, sodium and urea. Baseline was defined as the latest value recorded prior to the first dose of mepolizumab in Part A. Change from Baseline was defined as value at indicated time point minus Baseline value. All Part B visits (scheduled and unscheduled) post-Baseline were considered for Any-time Post-Baseline visit derivation. If participant had at least one value for categories To Low and/or To High along with To Normal or No Change then participant was counted under To Low and/or To High. If participant had values which belong only to To Normal or No Change then participant was counted under To Normal or No Change only. Any Time Post-Baseline values have been presented. | Baseline, from Week 20 and up to Week 72 | 
| Number of Participants With Any Time Change From Baseline Relative to Normal Range in Hematology Parameters for Part B | Blood samples were collected for analysis of basophils, eosinophils, leukocyte, monocyte, neutrophils, lymphocyte, platelets, mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), hemoglobin (Hgb), mean corpuscular volume (MCV), erythrocytes, hematocrit, and reticulocytes/erythrocytes (Ret/Ery). Baseline was defined as the latest value recorded prior to first dose of mepolizumab in Part A. Change from Baseline was defined as value at indicated time point minus Baseline value. All Part B visits (scheduled and unscheduled) post-Baseline were considered for Any-time Post-Baseline visit derivation. If participant had at least one value for categories To Low and/or To High along with To Normal or No Change then participant was counted under To Low and/or To High. If participant had values which belong only to To Normal or No Change then participant was counted under To Normal or No Change only. Any Time Post-Baseline values have been presented. | Baseline, from Week 20 and up to Week 80 | 
| Number of Participants With Abnormal Findings for Urinalysis Parameters in Part B | Urine samples were collected from participants at indicated time points for analysis of urinalysis parameters including Specific gravity and potential of hydrogen (pH) of urine, presence of glucose, protein, blood and ketones in urine by dipstick test. Microscopic examination was performed if blood or protein was abnormal. Only those participants with data available at the specified time points were analyzed. | From Week 20 and up to Week 72 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Body Weight-adjusted Apparent Clearance of Mepolizumab for Part A | PK samples were collected at pre-dose on Weeks 4 and 8; and at Weeks 9, 12, 16 and 20 post-dose. The body weight-adjusted apparent clearance was compared between adults and participants aged 6 to 11 years old with severe eosinophilic asthma when mepolizumab was administered subcutaneously. Point estimate and 90% confidence interval (CI) for participants aged 6 to 11 years (centered to a mean bodyweight of 70 kg) was compared with the historic adult estimated body-weight adjusted clearance of 0.22 L/day, around which a proposed 80-125% interval was applied i.e. 0.18-0.28 L/day. Assuming an absolute bioavailability of 75% this corresponds to an apparent clearance of 0.29 L/day with the proposed 80% to 125% interval of 0.23 to 0.36 L/day. Note the average bodyweight of 70kg (mean body weight observed in adults) was not observed in the study. | Pre-dose on Weeks 4 and 8; Weeks 9, 12, 16 and 20 post-dose | 
| Change From Baseline in Asthma Control Questionnaire-7 (ACQ-7) at Week 12 in Part A | ACQ-7 is a simple questionnaire to measure the adequacy of asthma control and change in asthma control which occurs either spontaneously or a result of treatment. The ACQ-7 uses a 7-point scale (0=no impairment, 6= maximum impairment for symptoms and rescue use; and 7 = category for forced expiratory volume in 1 second [FEV1]%). The instrument has a reported high test-retest reproducibility with an intraclass correlation coefficient =0.90. The minimally important change in score is 0.5. Baseline was defined as the latest value recorded prior to the first dose of mepolizumab. Change from Baseline was calculated as score obtained at Week 12 minus Baseline Score. Pharmacodynamic Outcome (PDo) Population included all participants who received at least one dose of mepolizumab beginning at Visit 2 and having at least one Part A assessment of pharmacodynamic outcomes. | Baseline and Week 12 | 
| Change From Baseline in Asthma Control Questionnaire-7 (ACQ-7) at Weeks 4,8,16 and 20 in Part A | ACQ-7 is a simple questionnaire to measure the adequacy of asthma control and change in asthma control which occurs either spontaneously or a result of treatment. The ACQ-7 uses a 7-point scale (0=no impairment, 6= maximum impairment for symptoms and rescue use; and 7=category for FEV1%). The instrument has a reported high test-retest reproducibility with an intraclass correlation coefficient =0.90. The minimally important change in score is 0.5. Baseline was defined as the latest value recorded prior to the first dose of mepolizumab. Change from Baseline was calculated as score obtained at the indicated time point minus Baseline Score. Only those participants with data available at the specified time points were analyzed (represented by n=X in the category titles). | Baseline and Weeks 4,8,16 and 20 | 
| Change From Baseline in Childhood Asthma Control Test (C-ACT) at Week 12 for Part A | The C-ACT assesses asthma control in children 4-11 years of age. The C-ACT is a 7-question, 2-part questionnaire, with items 1 to 4 were completed by the child (with assistance from a caregiver, as needed) and items 5 to 7 were completed by the caregiver. A total sum score based upon responses to all items was calculated to provide an overall measure of asthma control. The derived C-ACT score ranges from 0 (maximum impairment) to 27 (no impairment), where higher scores represent a better outcome. Baseline was defined as the latest value recorded prior to the first dose of mepolizumab. Change from Baseline was calculated as score obtained at Week 12 minus Baseline Score. | Baseline and Week 12 | 
| Change From Baseline in C-ACT at Weeks 4,8,16 and 20 in Part A | The C-ACT assesses asthma control in children 4-11 years of age. The C-ACT is a 7-question, 2-part questionnaire, with items 1 to 4 were completed by the child (with assistance from a caregiver, as needed) and items 5 to 7 were completed by the caregiver. A total sum score based upon responses to all items was calculated to provide an overall measure of asthma control. The derived C-ACT score ranges from 0 (maximum impairment) to 27 (no impairment), where higher scores represent a better outcome. Baseline was defined as the latest value recorded prior to the first dose of mepolizumab. Change from Baseline was calculated as score obtained at the indicated time point minus Baseline Score. Only those participants with data available at the specified time points were analyzed (represented by n=X in the category titles). | Baseline and Weeks 4,8,16 and 20 | 
| Number of Participants With on Treatment SAEs and Non-SAEs in Part A | An 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. Any untoward event resulting in death, life threatening, requires hospitalization or prolongation of existing hospitalization, results in disability/incapacity, congenital anomaly/birth defect, any other situation according to medical or scientific judgment or all events of possible drug-induced liver injury with hyperbilirubinemia were categorized as SAE. Participants who received any of the study treatment and had any on-treatment non-SAE or SAE (defined as events occurring from the first dose until 28 days after the last dose of mepolizumab) were considered for analysis. | Up to Week 20 | 
| Number of Participants With Any Time Change From Baseline Relative to Normal Range in Hematology Parameters in Part A | Blood samples were collected for analysis of basophils, eosinophils, leukocyte, monocyte, neutrophils, lymphocyte, platelet count, MCH, MCHC, Hgb, MCV, erythrocytes, hematocrit, and Ret/Ery. The Baseline was the latest value recorded prior to the first dose of mepolizumab. Change from Baseline was defined as value at indicated time point minus Baseline value. Any time post Baseline = all visits (scheduled and unscheduled) post Baseline was considered for this visit derivation. If participant had at least one value for categories To Low and/or To High along with To Normal or No Change then participant was counted under To Low and/or To High. If participant had values which belong only to To Normal or No Change then participant was counted under To Normal or No Change only. Only those participants with data available at the specified time points were analyzed (represented by n=X in the category titles). Any Time Post-Baseline values have been presented. | Baseline and up to Week 20 | 
| Number of Participants With Any Time Change From Baseline Relative to Normal Range in Clinical Chemistry Parameters in Part A | Blood samples were collected for analysis of ALT, ALP, AST, GGT, albumin, protein, total billirubin, creatinine, direct billirubin, urate, calcium, CO2, chloride, glucose, potassium, sodium and urea. Baseline was defined as the latest value recorded prior to the first dose of mepolizumab. Change from Baseline was defined as value at indicated time point minus Baseline value. Any time post Baseline = all visits (including scheduled and unscheduled) post Baseline was considered for this visit derivation. If participant had at least one value for categories To Low and/or To High along with To Normal or No Change then participant was counted under To Low and/or To High. If participant had values which belong only to To Normal or No Change then participant was counted under To Normal or No Change only. Any Time Post-Baseline values have been presented. | Baseline and up to Week 20 | 
| Number of Participants With Abnormal Findings for Urinalysis in Part A | Urine samples were collected from participants at indicated time points for analysis of urinalysis parameters including specific gravity and pH of urine, presence of glucose, protein, blood and ketones in urine by dipstick test. Microscopic examination was performed if blood or protein was abnormal. Only those participants with data available at the specified time points were analyzed. | Up to Week 20 | 
| Number of Participants With Positive Anti-mepolizumab Binding Antibodies and Neutralizing Antibodies Response in Part A | Blood sample for immunogenicity was collected for anti-mepolizumab binding antibodies and neutralizing antibodies response in Part A at indicated time points prior to study treatment administration. Number of participants with positive anti-mepolizumab binding antibodies and neutralizing antibodies response was summarized. Participant was considered 'Positive' if they had at least one positive post-baseline assay result. Any Time Post Baseline has been presented, which included all visits (including scheduled and unscheduled) post-baseline was considered for this visit derivation. Only those participants with data available at the specified time points were analyzed (represented by n=X in the category titles). | Baseline and Weeks 16 and 20 | 
| Change From Baseline in Sitting SBP and DBP in Part A | Sitting blood pressure measurements were performed in Part A at indicated time points. Measurements were done pre-infusion/injection with the participant sitting, having rested in this position for at least 5 minutes before each reading. The Baseline was defined as the latest value recorded prior to the first dose of mepolizumab. Change from Baseline was defined as value at indicated time point minus Baseline value. Only those participants with data available at the specified time points were analyzed (represented by n=X in the category titles). | Baseline and Weeks 4, 8, 9, 12, 16 and 20 | 
| Change From Baseline in Sitting Pulse Rate in Part A | Sitting pulse rate measurements was performed in Part A at indicated time points. Measurements were done pre-infusion/injection with the participant sitting, having rested in this position for at least 5 minutes before each reading. The Baseline was defined as the latest value recorded prior to the first dose of mepolizumab. Change from Baseline was defined as value at indicated time point minus Baseline value. Only those participants with data available at the specified time points were analyzed (represented by n=X in the category titles). | Baseline and Weeks 4, 8, 9, 12, 16 and 20 | 
| Ratio to Baseline in Absolute Blood Eosinophil Count at Weeks 32, 44, 56, 68, 72 and 80 for Part B | Blood samples were collected at the indicated time points for the analysis of eosinophil count. Baseline was defined as the latest value recorded prior to the first dose of mepolizumab in Part A. Ratio to Baseline was calculated as post-dose visit value/Baseline value. The analysis was based on Pharmacodynamic (Blood Eosinophils) (PDe) Population comprised of all participants receiving at least one dose of mepolizumab beginning at Visit 9 and having at least one Part B blood sample taken for blood eosinophil count. Only those participants with data available at the specified time points were analyzed (represented by n=X in the category titles). | Baseline and Weeks 32, 44, 56, 68, 72 and 80 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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pharmacokinetics, pediatric, Mepolizumab, subcutaneous, eosinophilic asthma, pharmacodynamics