Study of a New Medication for Childhood Chronic Immune Thrombocytopenia (ITP), a Blood Disorder of Low Platelet Counts That Can Lead to Bruising Easily, Bleeding Gums, and/or Bleeding Inside the Body.

Participants who achieved a platelet count >=50 Gi/L for at least 6 out of 8 weeks, between Weeks 5 and 12 of Part 1, were reported.

Percentage of participants who responded (defined as platelet count >= 50 Gi/L in absence of rescue) at least once up to week 12 of Part 1 (Odds of achieving a platelet count >=50 Gi/L during the first 12 weeks of Part 1)

Participants who achieved a platelet count >=50 Gi/L at any time during the first 12 weeks of Part 1 were reported.

Participants who achieved a platelet count >=50 Gi/L at any time during the first 6 weeks of Part 1 were reported.

The weighted mean platelet count is defined as "the area under the platelet-time curve divided by the duration of the study (12 weeks)". Weighted mean platelet counts from baseline to week 12 of the randomized period was compared between placebo and eltrombopag using an analysis of covariance model (ANCOVA) adjusting for baseline platelet count and age cohort. For each subject the area between two adjacent visits with platelet counts was calculated. The area was calculated for all pairs of adjacent visits starting at Day 1 of randomized period and then the total sum of all the areas was divided by the total duration of time during the randomized period. For each subject, this method calculates an 'average' platelet count and it allows the possibility that subjects may have had different number of assessments during different times relative to baseline.

The maximum duration for which a participant continuously maintained a platelet count >=50 Gi/L was calculated and summarized for the first 12 weeks of Part 1. 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 participant 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.

Rescue treatment is 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.

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; 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. Baseline was defined as the Day 1 assessment or the latest possible screening assessment.

Participants who achieved a platelet count >=50 Gi/L at any time during Part 2 (up to Week 24) were reported.

Platelet response was analyzed after Week 4 for the eltrombopag-only period to allow participants who had been randomized to placebo in the Randomized Period time to escalate to their optimal dose of eltrombopag. Participants with non-weekly assessments were assumed to have maintained a positive response for each week between two assessments that had positive responses. If the participant 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.

The maximum duration for which a participant continuously maintained a platelet count of >=50 Gi/L was calculated and summarized for the 24 weeks of eltrombopag dosing (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 the participant 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 who discontinued or had a sustained reduction of a baseline immune (idiopathic) thrombocytopenic purpura (ITP) medication during the 24 weeks of Part 2 (Open-Label Period) and without requiring subsequent rescue therapy. For participants randomized to placebo in Part 1, Baseline is defined as Week 13 of Part 1. For participants randomized to eltrombopag in Part 1, Baseline is defined as Day 1 of Part 1. A sustained reduction was defined as a reduction for 4 weeks or more.

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.

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 = Grade 1 to 4; no clinically significant bleeding = Grade 0 to 1; clinically significant bleeding = Grade 2 to 4.

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.

Clinical chemistry parameters were summarized according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE), version 4.0: Grade 0 (G0), none; Grade 1 (G1), mild; Grade 2 (G2), moderate; Grade 3 (G3), severe; Grade 4 (G4), life-threatening or disabling. Clinical chemistry parameters included: aspartate amino transferase (AST), alkaline phosphatase (ALP), total bilirubin, albumin, alanine amino transferase (ALT), prothrombin international normalized ratio (PT INR), activated partial thromboplastin time (APTT), and creatinine. The Baseline value is defined as the value taken at Day 1 or, if missing, the latest non-missing Screening value. For serum creatinine, due to the variations in creatinine, the average of the Screening and the Day 1 values will be used as Baseline. The maximum post-Baseline toxicity grade includes any scheduled or unscheduled post-Baseline assessment during Part 1.

Clinical chemistry parameters were summarized according to the NCI CTCAE, version 4.0: G0, none; G1, mild; G2, moderate; G3, severe; G4, life-threatening or disabling. Clinical chemistry parameters included: AST, ALP, total bilirubin, albumin, ALT, and creatinine. For participants randomized to Placebo in Part 1, the BL value for Part 2 is defined as the value taken at Week 13 of Part 1. For serum creatinine, the value taken at Week 13 of Part 1 will be used as BL. For participants randomized to Eltrombopag in Part 1, the BL value is defined as the value taken on Day 1 or, if missing, the latest non-missing Screening value. For serum creatinine, due to the variations in creatinine, the average of the Screening and the Day 1 values will be used as BL. For participants who do not have both a Screening and Day 1 value, the Screening or Day 1 value will be used as BL. The maximum post-BL toxicity grade includes any scheduled or unscheduled post-BL assessment.

Hematology parameters were summarized according to the NCI CTCAE, version 4.0: G0, none; G1, mild; G2, moderate; G3, severe; G4, life-threatening or disabling. Hematology parameters included: leukocytes, neutrophils, hemoglobin (increased), hemoglobin (anemia), lymphocytes (increased), and lymphocytes (decreased). The Baseline value is defined as the value taken at Day 1 or, if missing, the latest non-missing Screening value. The maximum post-Baseline toxicity grade includes any scheduled or unscheduled post-Baseline assessment during Part 1.

Hematology parameters were summarized according to the NCI CTCAE, version 4.0: G0, none, G1, mild; G2, moderate; G3, severe; G4, life-threatening or disabling. Hematology parameters included: leukocytes, neutrophils, hemoglobin (increased), hemoglobin (anemia), lymphocytes (increased), and lymphocytes (decreased). For participants randomized to Placebo in Part 1, the BL value for Part 2 is defined as the value taken at Week 13 of Part 1. For participants randomized to Eltrombopag in Part 1, the BL value is defined as the value taken on Day 1 or, if missing, the latest non-missing Screening value. For participants who do not have both a Screening and Day 1 value, the Screening or Day 1 value will be used as BL. The maximum post-BL toxicity grade includes any scheduled or unscheduled post-BL assessment.

Vital sign measurements were taken before any blood draws and included systolic blood pressure(SBP), diastolic blood pressure(DBP), and heart rate(HR). The number of participants are reported with vital sign data falling outside the standard reference ranges RR as reference range high(RRH) and reference range low(RRL). The Baseline(BL) value is defined as the value taken at Day 1 or if missing, the latest non-missing SCR value. RR for Blood Pressure (mmHg) are read as: Lower Limit of Normal, Normal Range, Upper Limit of Normal. For Ages 1 to 5 years (yrs) ranges are SBP <85, 85 to 115, >115; DBP <45, 45 to70, >70. Ages 6 to 11 yrs: SBP <85, 85 to 120, >120;, DBP <50, 50 to 75, >75. Ages 12 to 17 yrs: SBP <95, 95 to 135, >135; DBP <55, 55 to 85, >85. RR for HR(bpm) are ages 1 to < 3 yrs: <90, 90 to 140, >140; ages 3 to < 5 yrs: <75, 75 to 130, >130, ages 5 to < 8yrs: <65, 65 to 115, >115; ages 8 to < 12yrs: <55, 55 to 110, >110; and ages 12 to 18 yrs: <55, 55 to 110, >110.

Vital sign measurements were taken before any blood draw and included systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate(HR). The number of participants are reported with vital sign data falling outside the standard RR as reference range high(RRH) and reference range low(RRL) from SCR up to Week 24 of Part 2 and from Follow-up Week 1 to Week 4. RR for Blood Pressure(mmHg) are read as: Lower Limit of Normal, Normal Range, Upper Limit of Normal. For Ages 1 to 5 years (yrs) ranges are SBP <85, 85 to 115, >115; DBP <45, 45 to70, >70. Ages 6 to 11 yrs: SBP <85, 85 to 120, >120; DBP <50, 50 to 75, >75. Ages 12 to 17 yrs: SBP <95, 95 to 135, >135; DBP <55, 55 to 85, >85. RR for HR (bpm) are ages 1 to < 3 yrs: <90, 90 to 140, >140; ages 3 to < 5 yrs: <75, 75 to 130, >130, ages 5 to < 8yrs: <65, 65 to 115, >115; ages 8 to < 12yrs: <55, 55 to 110, >110; and ages 12 to 18 yrs: <55, 55 to 110, >110.

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. Change in visual acuity results are presented as No (no change from Baseline), Not Clinically Significant (NCS), Improvement, and Worsening since Baseline. The Baseline value was obtained at the Screening Visit.

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. Change in visual acuity results are presented as No Change, NCS, Improvement, and Worsening since Baseline. The Baseline value was obtained at the Screening Visit.

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. Change in visual acuity results are presented as No Change, NCS, Improvement, and Worsening since Baseline. The Baseline value was obtained at the Screening Visit.

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 worsening visual acuity due to cataracts at Week 12 of Part 1 are presented. 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. The number of participants with worsening visual acuity due to cataracts at Week 24 of Part 2 are presented. 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. The number of participants with worsening visual acuity due to cataracts at Follow-up Week 24 are presented. Change due to cataracts is categorized as "Yes" or "No."

Single PK samples were collected at each visit during Part 1 Weeks 2, 4, 6, 8, 10, 12 and at each weekly or monthly visit during Part 2 Weeks 1-12 (Study Weeks 13-37). 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. The AUC(0-t) for a 50mg dose was estimated for each cohort. From the final model, a single value of each PK parameter was estimated for each subject, and geometric mean (95% CI) values are presented for each cohort for a 50mg dose.

Single PK samples were collected at each visit during Part 1 Weeks 2, 4, 6, 8, 10, 12 and at each weekly or monthly visit during Part 2 Weeks 1-12 (Study Weeks 13-37). The concentration data were pooled across visits to identify population PK and variability parameter estimates and covariate effects. Cmax is defined as the maximum observed concentration. The Cmax for a 50mg dose was estimated for each cohort. From the final model, a single value of each PK parameter was estimated for each subject, and geometric mean (95% CI) values are presented for each cohort for a 50mg dose.

Single PK samples were collected at each visit during Part 1 Weeks 2, 4, 6, 8, 10, 12 and at each weekly or monthly visit during Part 2 Weeks 1-12 (Study Weeks 13-37). The concentration data were pooled across visits to identify population PK and variability parameter estimates and covariate effects. CL/F is defined as the apparent oral clearance from plasma and Q/F is defined as apparent intercompartmental clearance. These parameters are dose independent. From the final model, a single value of each PK parameter was estimated for each subject, and geometric mean (95% CI) values are presented for each cohort.

Single PK samples were collected at each visit during Part 1 Weeks 2, 4, 6, 8, 10, 12 and at each weekly or monthly visit during Part 2 Weeks 1-12 (Study Weeks 13-37). The concentration data were pooled across visits to identify population PK and variability parameter estimates and covariate effects. Vc/F is defined as the volume of the central (e.g. plasma) compartment and Vp/F is defined as the volume of the peripheral compartment. These parameters are dose independent. From the final model, a single value of each PK parameter was estimated for each subject, and geometric mean (95% CI) values are presented for each cohort.

Single PK samples were collected at each visit during Part 1 Weeks 2, 4, 6, 8, 10, 12 and at each weekly or monthly visit during Part 2 Weeks 1-12 (Study Weeks 13-37). The concentration data were pooled across visits to identify population PK and variability parameter estimates and covariate effects. Ka is defined as the absorption rate constant. This parameter is dose independent, and the population estimate Ka is reported.