Efficacy and Safety Study of Eltrombopag in Pediatric Patients With Thrombocytopenia From Chronic Idiopathic Thrombocytopenic Purpura (ITP)

Sustained platelet response between the treatment groups was assessed by determining the number of participants who achieved a platelet count >=50 Gi/L during treatment with eltrombopag in >= 60% of assessments between Day 15 and Day 43 in the absence of rescue treatment were reported here.

The weighted mean platelet count is defined as the area under the platelet-time curve divided by the duration of the treatment (12 weeks). Based on the Analysis of Covariance (ANCOVA) model, the weighted mean platelet count is the sum of the Baseline count plus the age cohort plus the treatment. Baseline was defined as the platelet count taken on Day 1 or within 48 hours prior to the first dose of treatment.

The percentage of participants achieving platelet counts >=50Gi/L at least once at any time during the 24 weeks of eltrombopag treatment were reported.

The percentage of participants achieving platelet counts >=50Gi/L at least once at any time during the 24 weeks of eltrombopag treatment during Part 2/3 of the study were reported. Participants randmoized to receive eltrombopag for 7 weeks in Part 2 continued receiving eltrombopag for an additional 17 weeks in Part 2/3 (for a total of 24 weeks of treatment) up to Study Week 24. Participants randomized to receive placebo for 7 weeks in Part 2, received 24 weeks of eltrombopag in Part 2/3 (for a total of 24 weeks of treatment) up to Study Week 31.

The area under the concentration-time curve over the dosing interval (AUC0-t) data was collected to estimate primary model-based PK parameters. PK samples were collected within 3 hours prior to dosing and 2, 4, 6, 8 and 24 hours after dosing. Doses were normalized to 50mg for comparison. PK samples were collected at each on-treatment visit during Part 1, Part 2, and Part 2/3. The concentration data were pooled across visits to identify population PK and variability parameter estimates and covariate effects. AUC(0-t) is defined as the area under the concentration-time curve over the dosing interval. From the final model, a single value of AUC(0-t) was estimated for each subject, and geometric mean (95% CI) values are presented for each cohort for a 50mg dose.

The maximum observed concentration (Cmax) and the concentration at the end of the dosing interval (Ct) data were collected to estimate primary model-based PK parameters. PK samples were collected within 3 hours prior to dosing and 2, 4, 6, 8 and 24 hours after dosing. Doses were normalized to 50mg for comparison. PK samples were collected at each on-treatment visit during Part 1, Part 2, and Part 2/3. The concentration data were pooled across visits to identify population PK and variability parameter estimates and covariate effects. From the final model, a single value of Cmax and Ct were estimated for each subject, and geometric mean (95% CI) values are presented for each cohort for a 50mg dose.

The time to maximum concentration (tmax) was collected to estimate primary model-based PK parameters. PK samples were collected within 3 hours prior to dosing and 2, 4, 6, 8 and 24 hours after dosing. PK samples were collected at each on-treatment visit during Part 1, Part 2, and Part 2/3. The concentration data were pooled across visits to identify population PK and variability parameter estimates and covariate effects. From the final model, a single value of tmax was estimated for each subject, and geometric mean (95% CI) values are presented for each cohort for a 50mg dose.

The apparent plasma clearance following oral dosing of eltrombopag (CL/F) was collected to estimate primary model-based PK parameters. PK samples were collected within 3 hours prior to dosing and 2, 4, 6, 8 and 24 hours after dosing. PK samples were collected at each on-treatment visit during Part 1, Part 2, and Part 2/3. The concentration data were pooled across visits to identify population PK and variability parameter estimates and covariate effects. From the final model, a single value of CL/F was estimated for each subject, and geometric mean (95% CI) values are presented for each cohort for a 50mg dose.

The maximum duration for which a participant continuously maintained a platelet count >=50 Gi/L in the absence of rescue treatment was calculated and summarized during the 24 weeks of eltrombopag treatment in Part 2. Participants with non-weekly assessments were assumed to have maintained a positive response for each week between two assessments that had positive responses. If a particpant achieved a positive response at an assessment and then achieved a negative response at the next assessment, then it was assumed that the participant had achieved a positive response for one day. Excludes periods from initiation of rescue medication until platelet count falls to below 50Gi/L, irrespective of platelet count

The maximum duration for which a participant continuously maintained a platelet count >=50 Gi/L in the absence of rescue treatment was calculated and summarized during the 24 weeks of eltrombopag treatment in Part 2/3. Participants with non-weekly assessments were assumed to have maintained a positive response for each week between two assessments that had positive responses. If a particpant achieved a positive response at an assessment and then achieved a negative response at the next assessment, then it was assumed that the participant had achieved a positive response for one day. Participants randmoized to receive eltrombopag for 7 weeks in Part 2 continued receiving eltrombopag for an additional 17 weeks in Part 2/3 (for a total of 24 weeks of treatment) up to Study Week 24. Participants randomized to receive placebo for 7 weeks in Part 2, received 24 weeks of eltrombopag in Part 2/3 (for a total of 24 weeks of treatment) up to Study Week 31.

The participants who discontinued (dis) or had a sustained reduction (red) of a Baseline (BL) ITP medication for at least one day during the period of Day 1 of Part 1 to the last dose of study medication +1 day are reported. The denominator is the number of subjects taking an ITP medication at baseline. For participants in Part 1, Baseline is defined as Day 1 of Part 1. A sustained reduction is defined as reduction for 4 weeks or more. An attempted red or dis is a decrease in the dose or frequency from the BL dose or frequency of an ITP medication for at least one day during the period Part 1 Day 1 to the last dose of study medication + 1 day.

Participants who discontinued (dis) or had a sustained reduction (red) of a Baseline (BL) ITP medication for at least one day during the period of Day 1 of Part 2/3 to the last dose of study medication +1 day are reported. The denominator is the number of subjects taking an ITP medication at baseline. For participants randomized to placebo in Part 2, BL is defined as Week 7 of Part 2. For participants randomized to eltrombopag in Part 2, BL is defined as Day 1 of Part 2. A sustained reduction is defined as reduction for 4 weeks or more. An attempted reduction or discontinuation is a decrease in the dose or frequency from the BL dose or frequency of an ITP medication for at least one day during the period Part 2/3 Day 1 to the last dose of study medication + 1 day.

Rescue treatment was defined as either a new immune (idiopathic) thrombocytopenic purpura (ITP) medication, an increase in the dose of a concomitant ITP medication from Baseline, a platelet transfusion, or a splenectomy. For particpants randomized to placebo in Part 2, Baseline is defined as Week 7 of Part 2. For participants randomized to eltrombopag in Part 2, Baseline is defined as Day 1 of Part 2. Participants randmoized to receive eltrombopag for 7 weeks in Part 2 continued receiving eltrombopag for an additional 17 weeks in Part 2/3 (for a total of 24 weeks of treatment) up to Study Week 24. Participants randomized to receive placebo for 7 weeks in Part 2, received 24 weeks of eltrombopag in Part 2/3 (for a total of 24 weeks of treatment) up to Study Week 31.

The KIT questionnaire measures the impact on the quality of life determined by the participant and the guardian by self reported outcomes at Baseline or the Screening Visit, after 6 weeks of treatment, after 12 weeks of treatment and at the end of treatment or withdrawal from the study. The KIT total score is calculated from the scores of each of the individual questions from Q1 - Q26 (excluding any answer that is 'Not applicable'). The code list used for the individual question scores is: 1 = never, 2 = seldom, 3 = sometimes, 4 = often, 5 = always and 9 = not applicable. The range of values the total score can take is 0 (worst) to 100 (best). For subjects under the age of six, the family questionnaire (parental proxy) has been used.

The KIT questionnaire measures the impact on the quality of life determined by the participant and the guardian by self reported outcomes at Baseline or the Screening Visit, after 6 weeks of treatment or withdrawal from the study. The KIT total score is calculated from the scores of each of the individual questions from Q1 - Q26 (excluding any answer that is 'Not applicable'). The code list used for the individual question scores is: 1 = never, 2 = seldom, 3 = sometimes, 4 = often, 5 = always and 9 = not applicable. The range of values the total score can take is 0 (worst) to 100 (best). For subjects under the age of six, the family questionnaire (parental proxy) has been used.

The KIT questionnaire measures the impact on the quality of life determined by the participant and the guardian by self reported outcomes at Baseline or the Screening Visit, after 6 weeks of treatment, after 12 weeks of treatment and at the end of treatment or withdrawal from the study. The KIT total score is calculated from the scores of each of the individual questions from Q1 - Q26 (excluding any answer that is 'Not applicable'). The code list used for the individual question scores is: 1=never, 2=seldom, 3=sometimes, 4=often, 5=always and 9=not applicable. The range of values the total score can take is 0 (worst) to 100 (best). For subjects under the age of six, the family questionnaire (parental proxy) has been used.

The WHO Bleeding Scale is a measure of bleeding severity with the following grades: Grade 0 = no bleeding, Grade 1 = petechiae, Grade 2 = mild blood loss, Grade 3 = gross bleeding and Grade 4 = debilitating blood loss. The WHO grades were dichotomized into the following categories: no bleeding=Grade 0; any bleeding=Grades 1 to 4; no clinically significant bleeding=Grades 0 to 1; clinically significant bleeding=Grades 2 to 4. For participants randomized to Placebo in Part 2, Baseline defined as Week 7 of Part 2. For participants randomized to Eltrombopag in Part 2, Baseline defined as Day 1 of Part 2.

The WHO Bleeding Scale is a measure of bleeding severity with the following grades: Grade 0 = no bleeding, Grade 1 = petechiae, Grade 2 = mild blood loss, Grade 3 = gross bleeding and Grade 4 = debilitating blood loss. The WHO grades were dichotomized into the following categories: no bleeding=Grade 0; any bleeding=Grades 1 to 4; no clinically significant bleeding=Grades 0 to 1; clinically significant bleeding=Grades 2 to 4. For participants randomized to Placebo in Part 2, Baseline defined as Week 7 of Part 2. For participants randomized to Eltrombopag in Part 2, Baseline defined as Day 1 of Part 2.

Clinical chemistry parameters included: aspartate amino transferase (AST, reference range [RR]: 0-38 International Units per Liter [IU/L]), alkaline phosphatase (ALP: RR: 50 - 375 IU/L), total bilirubin (RR: 3.42 - 22.23 micromoles [umol]/L), albumin grams [g/L], alanine amino transferase (ALT, RR: 5-30 IU/L), prothrombin international normalized ratio (PT INR, RR-0.9 - 1.2), activated partial thromboplastin time (APTT, RR: 24.2 - 32.9 seconds), glucose (RR: 4.107- 6.55018 millimoles [mmol]/L), potassium (3 - 5 mmol/L), and sodium (135 - 143 mmol/L). Baseline values were obtained at Day 1. The number of participants with the indicated clinical chemistry data outside of the reference range (with high and low) any time post-Baseline are presented. Anytime post-Baseline assesments included any scheduled and unscheduled post-Baseline assessment

Hematology parameters included: erythrocytes (RR: 4.2 - 6.1 teragrams per liter [TI/L]), hemoglobin (RR: 125 - 165 g/L), hematocrit (RR: 0.36 - 0.46), platelets (RR: 170 - 430 gigagrams per liter [GI/L]), mean platelet volume (MPV, RR: 4 - 14 femotoliter [fL]), leukocytes (RR: 3.4 - 11.2 GI/L), total neutrophils (RR: 2.1 - 4.9 GI/L), lymphocytes (RR: 1.4 - 2.9 GI/L), monocytes (RR: 0.2 - 0.9 GI/L), eosinophils (RR: 0.2 - 0.7 GI/L), and basophils (RR: 0.02 - 0.12 GI/L). Baseline values were obtained at Day 1. The number of participants with the indicated hematology parameters data outside of the reference range (with high and low) any time post-baseline are presented. Anytime post-Baseline assesments included any scheduled and unscheduled post-Baseline assessment

Renal parameters included: creatinine (RR: 44.2 - 88.4 umol/L), creatinine clearance derived (RR: 89.0 - 165.0 milliliter per minute [ ml/min]), protein/creatinine (RR: 0.113- 18.0992 microgram per millimoles [mg/mmol]), and urea (RR: 1.785- 8.925 mmol/L). Baseline values were obtained at Day 1. The number of participants with the indicated renal parameters data outside the reference range (with high and low) any time post-Baseline are presented. Anytime post-Baseline assesments included any scheduled and unscheduled post-baseline assessment

Urine microscopy included Red Blood Cell (RBC) casts, white blood cell (WBC) casts, and epithelial renal tubular cell casts. Urine microscopy data was reviewed by the Medical Monitor in order to classify the results as positive or negative. The number of participants with a positive result at any time post Baseline were reported. A positive result indicated if the result was positive for at least one of RBC casts, WBC casts, or epithelial renal tubular cell casts.

Urine microscopy included Red Blood Cell (RBC) casts, white blood cell (WBC) casts, and epithelial renal tubular cell casts. Urine microscopy data was reviewed by the Medical Monitor in order to classify the results as positive or negative. The nmber of participants with positive finding at Baseline and at anytime post-Baseline (Post-BL) were reported. Baseline was defined as the value obtained at the first visit before treatment (Pre-trt). A positive result indicated if the result was positive for at least one of RBC casts, WBC casts, or epithelial renal tubular cell casts.

Urine microscopy included Red Blood Cell (RBC) casts, white blood cell (WBC) casts, and epithelial renal tubular cell casts. Urine microscopy data was reviewed by the Medical Monitor in order to classify the results as positive or negative. The number of participants with positive finding at Baseline and at anytime post-Baseline (Post-BL) were reported. Baseline was defined as the value obtained at the first visit before treatment (Pre-trt). A positive result indicated if the result was positive for at least one of RBC casts, WBC casts, or epithelial renal tubular cell casts. Participants randomized to receive eltrombopag for 7 weeks in Part 2 continued receiving eltrombopag for an additional 17 weeks in Part 2/3 (for a total of 24 weeks of treatment) up to Study Week 24. Participants randomized to receive placebo for 7 weeks in Part 2, received 24 weeks of eltrombopag in Part 2/3 (for a total of 24 weeks of treatment) up to Study Week 31.

Vital sign assessments included systolic blood pressure (SBP) and diastolic blood pressure (DBP) measurements that were measured before any blood draw at the following scheduled time points: Screening, Day 1, each week from Week 1 to Week 24, at each Follow-up week (Week 1-4) and the maximum post- Baseline (BL) visit. BL is defined as the value obtained on Day 1of treatment. The maximum post-BL visit (MPB) included any scheduled and unscheduled post-BL assessment. Reference ranges (RR) for SBP (mmHg) (Lower limit of normal, normal, Upper limit of normal) for Cohort 1: <85, 85-115, >115; for Cohort 2: <85, 85-120,>120; and Cohort 3: <95, 95-135, >135. RR for DBP (mmHg) for Cohort 1: <45, 45-70,>70; for Cohort 2: <50, 50-75, >75; and Cohort 3: <55, 55-85, >85.

Respiratory rate was measured at the following scheduled time points: Screening, Day 1, each week from Week 1 to Week 24, and at each Follow-up Weeks 1-4. Baseline is defined as the value obtained on Day 1 of treatment. The maximum post-Baseline value included any scheduled and unscheduled post-Baseline assessment.

Respiratory rate was measured at the following scheduled time points: Screening, Day 1, each week from Week 1 to Week 24, and at each Follow-up Weeks 1-4. Baseline is defined as the value obtained on Day 1 of treatment. The maximum post-Baseline value included any scheduled and unscheduled post-Baseline assessment.

Respiratory rate was measured at the following scheduled time points: Screening, Day 1, each week from Week 1 to Week 24, and at each Follow-up Weeks 1-4. Baseline is defined as the value obtained on Day 1 of treatment. The maximum post-Baseline visit included any scheduled and unscheduled post-Baseline assessment. Participants randomized to receive eltrombopag for 7 weeks in Part 2 continued receiving eltrombopag for an additional 17 weeks in Part 2/3 (for a total of 24 weeks of treatment) up to Study Week 24. Participants randomized to receive placebo for 7 weeks in Part 2, received 24 weeks of eltrombopag in Part 2/3 (for a total of 24 weeks of treatment) up to Study Week 31.

Pulse rate was measured at the following scheduled time points: Screening, Day 1, each week from Week 1 to Week 24, and at each Follow-up Weeks 1-4. Baseline is defined as the value obtained on Day 1 of treatment. The maximum post-Baseline (MPB) visit included any scheduled and unscheduled post-Baseline assessment..

Pulse rate was measured at the following scheduled time points: Screening, Day 1, each week from Week 1 to Week 24, and at each Follow-up Weeks 1-4. Baseline is defined as the value obtained on Day 1 of treatment. The maximum post-Baseline visit included any scheduled and unscheduled post-Baseline assessment.

Pulse rate was measured at the following scheduled time points: Screening, Day 1, each week from Week 1 to Week 24, and at each Follow-up Weeks 1-4. Baseline is defined as the value obtained on Day 1 of treatment. The maximum post-Baseline visit included any scheduled and unscheduled post-Baseline assessment. Participants randomized to receive eltrombopag for 7 weeks in Part 2 continued receiving eltrombopag for an additional 17 weeks in Part 2/3 (for a total of 24 weeks of treatment) up to Study Week 24. Participants randomized to receive placebo for 7 weeks in Part 2, received 24 weeks of eltrombopag in Part 2/3 (for a total of 24 weeks of treatment) up to Study Week 31.

Urinalysis parameters included: urine protein (UP), urine glucose (UG), urine ketones (UK), urine occult blood (UOB), and pH. The dipstick test gives results in a semi-quantitative manner. UP was categorized as missing (MS), no result (NR), negative (Neg), Trace, 1+, 2+, 3+ and 4+. UG results were categorized as MS, NR, Neg, normal, 5, 15(1+), 30(2+), 60(3+), 110(4+)UK parameters were categorized as as MS, NR, Neg, Trace(5), Small(15), Moderate(40), Large(80), Large(160). UOB parameters were categorized as MS, NR, Neg, 1+, 2+, 3+, Non haemolysed trace, and haemolysed trace. PH results were categorized as MS. NR, normalresult, Neg, and range of pH (from 5-9in increments of 0.5). Data for indicated parameters was reported at Baseline (BL) and Week 24 (W24). The Baseline value was the measurement taken at Day 1.

Urinalysis parameters included: urine protein (UP), urine glucose (UG), urine ketones (UK), urine occult blood (UOB), and pH. The dipstick test gives results in a semi-quantitative manner. UP was categorized as missing (MS), no result (NR), negative (Neg), Trace, 1+, 2+, 3+ and 4+. UG results were categorized as MS, NR, Neg, normal, 5, 15(1+), 30(2+), 60(3+), 110(4+)UK parameters were categorized as as MS, NR, Neg, Trace(5), Small(15), Moderate(40), Large(80), Large(160). UOB parameters were categorized as MS, NR, Neg, 1+, 2+, 3+, Non haemolysed trace, and haemolysed trace. PH results were categorized as MS. NR, normalresult, Neg, and range of pH (from 5-9in increments of 0.5). Data for indicated parameters was reported at Baseline (BL) and Week 7 (W7). The Baseline value was the measurement taken at Day 1.

Urinalysis parameters included: urine protein (UP), urine glucose (UG), urine ketones (UK), urine occult blood (UOB), and pH. The dipstick test gives results in a semi-quantitative manner. UP was categorized as missing (MS), no result (NR), negative (Neg), Trace, 1+, 2+, 3+ and 4+. UG results were categorized as MS, NR, Neg, normal, 5, 15(1+), 30(2+), 60(3+), 110(4+)UK parameters were categorized as as MS, NR, Neg, Trace(5), Small(15), Moderate(40), Large(80), Large(160). UOB parameters were categorized as MS, NR, Neg, 1+, 2+, 3+, Non haemolysed trace, and haemolysed trace. PH results were categorized as MS. NR, normalresult, Neg, and range of pH (from 5-9in increments of 0.5). Data for indicated parameters was reported at Baseline (BL) and Week 24 (W24). The Baseline value was the measurement taken at Day 1.

An adverse event (AE) is defined as any untoward medical occurrence in a participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. A serious adverse event (SAE) is defined as any untoward medical occurrence that, at any dose: results in death, is life threatening, requires hospitalization or prolongation of existing hospitalization, results in disability or incapacity, or is a congenital anomaly or birth defect. Medical or scientific judgment should be exercised in other situations.

An adverse event (AE) is defined as any untoward medical occurrence in a participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. A serious adverse event (SAE) is defined as any untoward medical occurrence that, at any dose: results in death, is life threatening, requires hospitalization or prolongation of existing hospitalization, results in disability or incapacity, or is a congenital anomaly or birth defect. Medical or scientific judgment should be exercised in other situations.

An adverse event (AE) is defined as any untoward medical occurrence in a participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. A serious adverse event (SAE) is defined as any untoward medical occurrence that, at any dose: results in death, is life threatening, requires hospitalization or prolongation of existing hospitalization, results in disability or incapacity, or is a congenital anomaly or birth defect. Medical or scientific judgment should be exercised in other situations.

The visual acuity assessment was performed by an ophthalmologist or an optometrist under the guidance of an ophthalmologist. Visual acuity is defined as acuteness or clearness of vision. The number of participants with a change in visual acuity and worsening visual acuity due to cataracts since Baseline are presented for Part 1 Follow-up Visits at 3-months (FU3) and at 6-months (FU6). Change in visual acuity since Baseline is displayed under the left eye but applies to both eyes. Change in visual acuity (VA) is categorized as "yes" or "no". Change due to cataracts is categorized as "yes" or "no".

The visual acuity assessment was performed by an ophthalmologist or an optometrist under the guidance of an ophthalmologist. Visual acuity is defined as acuteness or clearness of vision. Number of participants with a change in visual acuity and change in visual acuity due to the worsening of cataracts since Baseline are presented for Part 2/3 Follow-up Visits at 3-months (FU3) and 6-months (FU6). Change in visual acuity since Baseline is displayed under the left eye but applies to both eyes. Change in visual acuity (VA) is categorized as "yes" or "no". Change due to cataracts is categorized as "yes" or "no".