Trial Outcomes & Findings for Pharmacokinetics and Pharmacodynamics of Mepolizumab Administered Subcutaneously in Children (NCT NCT02377427)

This was a multi-center, open-label study to assess the pharmacokinetics (PK) and pharmacodynamics (PD) of mepolizumab 40 or 100 milligrams (mg) subcutaneously administered to participants with severe eosinophilic asthma aged 6-11 years. This study consisted of two parts: Part A and Part B.

Part A consisted of pre-screening/ screening/ run-in, treatment, and Follow-up. Part B was long-term treatment and Follow-up phase. A total of 44 participants were screened and 36 were enrolled in Part A. Of which, 30 participants continued on treatment in Part B. Study was conducted in 4 countries (Japan, Poland, United Kingdom and United States).

Pharmacokinetics and Pharmacodynamics of Mepolizumab Administered Subcutaneously in Children

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.

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.

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.

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.

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.

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.

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.

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).

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).

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.

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.

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.

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.

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.

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).

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.

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).

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.

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.

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.

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.

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).

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).

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).

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).