Eltrombopag Phase III Study In Chinese Chronic ITP Patients

Study Overview
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Brief Summary
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This randomized, double-blind and open-label phase III study aimed to determine the efficacy, tolerance and safety of eltrombopag in Chinese chronic primary immune thrombocytopenia (ITP) adult subjects. This study was be conducted in Chinese adult chronic ITP subjects who had not responded to or had relapsed after previous treatment of ITP, including first line therapy and /or splenectomy. The primary objective of this study was to determine the efficacy of oral eltrombopag as a thrombopoietic agent treating previously treated chronic Chinese ITP patients compared to placebo. The secondary objective was to assess the safety and tolerability of eltrombopag when administered for 6 weeks to previously treated adult chronic ITP patients compared with placebo. In addition, the long-term efficacy and safety of eltrombopag treatment was also evaluated in the 24-week extension open-label phase after the double-blind phase as one of other study objectives. If the subject benefited from the eltrombopag treatment based on the investigator's discretion, the subject could continue on eltrombopag treatment until the commercial launch of eltrombopag in China. Furthermore, to understand the pharmacokinetics (PK) profile of eltrombopag and to explore the relationship between the PK and pharmacodynamics (PD) (platelet response), a PK/PD analysis was embedded in this phase III study and conducted in the same patient population who participated this phase III study.

Detailed Description
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This randomized, double-blind and open-label phase III study aimed to determine the efficacy, tolerance and safety of eltrombopag in Chinese chronic primary immune thrombocytopenia (ITP) adult subjects. This study was conducted in Chinese adult chronic ITP subjects who had not responded to or had relapsed after previous treatment for ITP, including first line therapy and /or splenectomy. The primary objective of this study was to determine the efficacy of oral eltrombopag as a thrombopoietic agent treating previously treated chronic Chinese ITP patients compared to placebo. The secondary objective was to assess the safety and tolerability of eltrombopag when administered for 6 weeks to previously treated adult chronic ITP patients compared to placebo. In addition, the long-term efficacy and safety of eltrombopag treatment was also evaluated in the 24-week extension open-label phase after the double-blind phase as one of other study objectives. If the subject benefited from the eltrombopag treatment based on the investigator's discretion, the subject could continue the eltrombopag treatment until the commercial launch of eltrombopag in China. Furthermore, to understand the pharmacokinetics (PK) profile of eltrombopag and to explore the relationship between the PK and pharmacodynamics (PD) (platelet response), a PK/PD analysis was embedded in this phase III study and conducted in the same patient population who participated this phase III study. 155 eligible subjects were randomized to either eltrombopag or matching placebo treatment in 2:1 ratio in stage 1 (the 8-week double blind stage). Randomization for stage 1 was stratified by splenectomy status (Yes/No), use of concomitant maintenance ITP therapy (Yes/No) and baseline platelet count (no more than 15×109/L, or >15×109/L). This study include 3 stages. The stage 1 was an 8-week double-blind, randomized, placebo-controlled treatment period. Following completion of Stage 1 and after completing the data cleanup of the initial 6 weeks, the investigator was be un-blinded to treatment assignment on an individual subject basis to enable appropriate starting dose selection for stage 2, a 24-week open-label treatment period. PK sampling and assessments occurred at the Week 2 visit during stage 2 of the study, when all subjects were receiving eltrombopag. After the completion of stage 2, subjects could continue the the eltrombopag treatment in stage 3, if he/she benefited from the continuous eltrombopag treatment based on the investigator's judgement. The initial dose of eltrombopag administration was an oral 25 mg once daily. During the 8 weeks double-blind treatment, dose of investigational product was adjusted according to the weekly subject platelet count. The eligible subjects who completed stage 1 (8 weeks of double-blind treatment period: the first 6 weeks data was used for primary endpoint analysis and the last 2 weeks for data cleanup period during which the blinded treatment continued) entered a voluntary open-label stage 2 (24-week open-label extension phase) in which subjects from both the eltrombopag group and placebo group had the opportunity to receive eltrombopag treatment. Subjects unwilling or unqualified (such as the subjects who met the stopping criteria) to participate in extension treatment attended follow-up visits for 4 weeks after the completion of the double-blind phase. During the open-label stage 2 phase all eligible subjects received open label eltrombopag treatment. The dose of eltrombopag was continuously adjusted according to the subject's platelet count. Following completion of Stage 2, if the subject benefited from the eltrombopag treatment based on the investigator's discretion, the subject could voluntarily enter stage 3, during which the subject continued eltrombopag treatment until the commercial launch of eltrombopag in C

Official Title
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A Multicenter, Randomized, Double-Blind and Open-label Phase III Study To Compare The Efficacy And Safety Of Eltrombopag With Placebo In Chinese Chronic ITP Patients

Conditions
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Purpura, Thrombocytopenic, Idiopathic and Hepatitis C

Intervention / Treatment
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* Drug: eltrombopag
* Drug: placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Subject is ≥18 years old. Diagnosed with ITP for at least 12 months prior to screening, and have a platelet count of <30 X109/L on Day 1 (or within 48 hours prior to dosing on Day 1). Patients who have no response or relapsed after splenectomy. Or patients who have not been splenectomised and have either not responded to one or more prior therapies (except splenectomy), or who have relapsed prior therapy. Previous therapy for ITP including rescue must have been completed at least 2 weeks prior to randomization. Subjects treated with maintenance immunosuppressive therapy must be receiving a dose that has been stable for at least 1 month. No pre-existing cardiac disease within the last 3 months. No arrhythmia known to increase the risk of thrombolic events (e.g. atrial fibrillation), or patients with a Corrected QT interval (QTc) >450msec or QTc >480 for patients with a Bundle Branch Block. No history of clotting disorder, other than ITP. A complete blood count (CBC), within the reference range, with the following exceptions: Platelets <30×109/L on Day 1 (or within 48hours of Day 1) is required for inclusion, Hemoglobin: females and males 10.0 g/dl are eligible for inclusion, Absolute neutrophil count (ANC) ≥1500/µL (1.5×109/L) is required for inclusion Blood chemistry test result no exceed normal by more than 20%. Total albumin must not be below the lower limit of normal (LLN) by more than 10%. Subject is non-childbearing potential of childbearing potential and use acceptable methods of contraception from two weeks prior to administration of study medication, throughout the study, and 28 days after completion or premature discontinuation from the study. Exclusion Criteria: Patients with any prior history of arterial or venous thrombosis, AND ≥ two of the following risk factors: hormone replacement therapy, systemic contraception (containing estrogen), smoking, diabetes, hypercholesterolemia, medication for hypertension, cancer, hereditary thrombophilic disorders (e.g., Factor V Leiden, ATIII deficiency, antiphospholipid syndrome, etc). Any clinically relevant abnormality, other than ITP,which in the opinion of the investigator makes the subject unsuitable for participation in the study. Female subjects who are nursing or pregnant at screening or pre-dose on Day 1. History of alcohol/drug abuse or dependence within 12 months of the study. Treatment with thrombopoietin or an investigational drug within 30 days or five half-lives (whichever is longer) preceding the first dose of study medication. Subjects who have previously received eltrombopag or any other thrombopoietin receptor agonist. Subject has consumed aspirin, aspirin-containing compounds, salicylates, anticoagulants, quinine or non-steroidal anti-inflammatories (NSAIDs) for >3 consecutive days within 2 weeks of the study start and until the end of the study. Consumption of any herbal or dietary supplements, excluding vitamin or mineral supplements, within 1 week of the study start. History of platelet aggregation that prevents reliable measurement of platelet counts. An abnormality in bone marrow examination result, other than ITP, identified on the screening examination, which in the opinion of the investigator makes the subject unsuitable for participation in the study (e.g. ≥MF-2 according to EU consensus scale [Thiele, 2005]) or suggests another primary diagnosis (e.g. Thrombocytopenia is secondary to another disease). Any laboratory or clinical evidence for HIV infection. Any clinical history for hepatitis C infection; chronic hepatitis B infection; or any evidence for active hepatitis at the time of subject screening. Laboratory test shows positive serology for Hepatitis C or Hepatitis B (HB) defined as a positive test for HBsAg. In addition, if negative for HBsAg but HBcAb positive (regardless of HBsAb status), a HB DNA test will be performed and if positive the subject will be excluded. Patients expected to require rescue on Day 1 of the study.

Ages Eligible for Study
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Minimum Age: 18 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: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Eltrombopag (ETB115)<br>Thrombopoietin- receptor (TPO-R) agonist | Drug: eltrombopag<br>* TPO-R agonist<br>* Other names: ETB115;|
| Placebo Comparator: Placebo<br>Placebo | Drug: placebo<br>* placebo<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Participants (Responders) Achieving a Platelet Count >=50×10^9/L After the First 6 Weeks of Stage 1 | The number of participants (responders) with platelet count >=50x10^9/L after 6 weeks of Stage 1 were compared between treatments using a logistic regression model adjusted for use of primary immune thrombocytopenia (ITP) medication at Baseline (yes/no), splenectomy (yes/no), Baseline platelet count <=15×10^9/L (yes/no) and treatment. Complete blood count including platelet count was done at Week 1, Week 2, Week 3, Week 4, Week 5 and Week 6. Primary Analysis Data Set: a participant who withdrawals from Stage 1 or is emergently unblinded was classified as a negative response from the time of withdrawal or unblinding date and for all subsequent visits. In the event of a participant dying, information for all subsequent assessments would be considered missing. All intermittent missing data (apart from withdrawals) will be treated as missing. | From the start of study treatment (Day 1) up to the end of Week 6 of Stage 1 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Participants Achieving a Platelet Count >=50×10^9/L at Least Once During the First 6 Weeks of Stage 1 | The number of participants (responders) with platelet count >=50×10^9/L at least once during the first 6 weeks of Stage 1 were compared between treatments using a logistic regression model adjusted for use of ITP medication at Baseline (yes/no), splenectomy (yes/no), Baseline platelet count <=15×10^9/L (yes/no) and treatment. Complete blood count including platelet count was done at Week 1, Week 2, Week 3, Week 4, Week 5 and Week 6. | From the start of study treatment (Day 1) up to the end of Week 6 of Stage 1 | 
| Number of Participants Achieving a Platelet Count >=30×10^9/L and at Least 2 Times the Baseline Platelet Count at Least Once During the 6 Weeks of Stage 1, the Whole Stage 2 and the Whole Stage 3 | The number of participants achieving a platelet count >=30×10^9/L and at least 2 times the Baseline platelet count at least once during the first 6 weeks of Stage 1 were analyzed. The Baseline platelet count is defined as the platelet count taken on Day 1 of the study or within 48 hours prior to the first dose of investigational product. Logistic regression analysis was adjusted for use of ITP medication at Baseline (yes/no), splenectomy (yes/no), Baseline platelet count <=15×10^9/L (yes/no) and treatment. Complete blood count including platelet count was done at Week 1, Week 2, Week 3, Week 4, Week 5 and Week 6. | From the start of study treatment (Day 1) up to the end of Stage 3 | 
| Number of Participants With Bleeding as Assessed Using the World Health Organization (WHO) Bleeding Scale | 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 blood loss, and grade 4 = debilitating blood loss. The WHO Bleeding Scale were dichotomized to indicate no bleeding vs bleeding, i.e. 0=grade 0 and 1=grades 1, 2, 3 or 4. Generalized linear mixed model was applied with a Logit canonical link function for repeated binary data, allowing for Baseline dichotomized WHO bleeding grade, use of ITP medication at Baseline (yes/no), splenectomy (yes/no), Baseline platelet count <=15×10^9/L (yes/no) and treatment as fixed effects, and the participant was treated as a random effect. Bleeding incidences were recorded at Screening, Week 1, Week 2, Week 3, Week 4, Week 5 and Week 6 for Stage 1, Baseline, Weeks 4, 8, 16, 20, 24 for Stage 2; Baseline, Weeks 25, 29, 73, 97, 121, 145, 169, 193, 217, 241, 265, 284 for Stage 3. Bleeding incidences at these time points are presented. | From the start of study treatment (Day 1) up to the end of Stage 3 | 
| Number of Participants With Clinically Significant Bleeding as Assessed Using the World Health Organization (WHO) Bleeding Scale | 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 blood loss, and grade 4 = debilitating blood loss. The WHO Bleeding Scale grades were dichotomized into the following categories: no clinically significant bleeding = Grade 0 to 1; clinically significant bleeding = Grade 2 to 4. Generalized linear mixed model with a Logit canonical link function for repeated binary data, allowing for Baseline dichotomized WHO bleeding grade, use of ITP medication at Baseline (yes/no), splenectomy (yes/no), Baseline platelet count <=15×10^9/L (yes/no) and treatment as fixed effects, and the participant was treated as a random effect. | From the start of study treatment (Day 1) up to the end of Stage 3 | 
| Time to Response | Time to response is defined as time from the startin of treatment to the first time of achieving a platelet count >=50x10^9/L during the first 6 weeks of Stage 1. Time to response is summarized using Kaplan-Meier estimates and compared between treatment groups using a stratified log-rank test, stratifying for the use of ITP medication at Baseline (yes/no), splenectomy (yes/no), Baseline platelet count <=15x10^9/L (yes/no). The pike estimator of the treatment hazard ratio is based on the stratified log-rank test. Complete blood count including platelet count was done at Week 1, Week 2, Week 3, Week 4, Week 5 and Week 6. | From the start of study treatment (Day 1) up to the end of Week 6 of Stage 1 | 
| Number of Participants Who Required Protocol-defined Rescue Treatment During the First 6 Weeks of Stage 1, Whole Stages 2 & 3 | Rescue treatment is defined as either a new ITP medication, an increase in dose of concomitant ITP medication from Baseline, a platelet transfusion, or a splenectomy. Logistic regression analysis was adjusted for use of ITP medication at Baseline (yes/no), splenectomy (yes/no), Baseline platelet count <=15x10^9/L (yes/no) and treatment. | From the start of study treatment (Day 1) up to the end of Stage 3 | 
| Number of Participants With a Platelet Count >=50×10^9/L During at Least 75% of Their Platelet Count Assessments | The number of participants with a platelet count >=50×10^9/L during at least 75% of their platelet count assessments was analyzed up to the end of Week 6 of Stage 1. Logistic regression analysis was adjusted for use of ITP medication at Baseline (yes/no), splenectomy (yes/no), Baseline platelet count <=15x10^9/L (yes/no) and treatment. Complete blood count including platelet count was done at Week 1, Week 2, Week 3, Week 4, Week 5 and Week 6. | From the start of study treatment (Day 1) up to the end of Stage 3 | 
| Total Duration of Time a Participant Had a Platelet Count >=50×10^9/L | Total duration of time a participant had platelet count >=50 x 10^9/L was analyzed using the van Elteren stratified rank test with stratification factors including the use of ITP medication at Baseline (yes/no), splenectomy (yes/no) and Baseline platelet count <=15x10^9/L (yes/no). Complete blood count including platelet count was done at Week 1, Week 2, Week 3, Week 4, Week 5 and Week 6. | From the start of study treatment (Day 1) up to the end of Stage 3 | 
| Maximum Period of Time a Participant Had a Platelet Count Continuously >= 50 ×10^9/L | Maximum period of time a participant had a platelet count continously >=50 x 10^9/L was analyzed using the van Elteren stratified rank test with stratification factors including the use of ITP medication at Baseline (yes/no), splenectomy (yes/no) and Baseline platelet count <=15x10^9/L (yes/no). Complete blood count including platelet count was done at Week 1, Week 2, Week 3, Week 4, Week 5 and Week 6. | From the start of study treatment (Day 1) up to the end of Stage 3 | 
| Number of Participants That Reduced or Discontinued Baseline Concomitant ITP Medications During Stage 2 and Stage 3 | The number of participants taking concomitant ITP medications on Day 1 of Stage 1 who had a decrease in the dose or frequency of ITP medication or stopped ITP medication at any point during Stage 2 or Stage 3 will be presented. The Baseline concomitant ITP medication for Stage 2 and Stage 3 is defined as ITP medications taken prior to the first dose of investigational product of Stage 1. This study is still ongoing and this endpoint can only be analyzed when the stage 2 and stage 3 complete. | From the start of Stage 2 to the end of Stage 3 | 
| Number of Participants With Any Adverse Event (AE) or Serious Adverse Event (SAE) | An AE is defined as any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a medicinal product whether or not considered related to the medicinal product.A SAE is any untoward medical occurrence that, at any dose results in death, is life-threatening, requires hospitalization or prolongation of existing hospitalization, is a congenital anomaly/birth defect or is associated with protocol specified liver injury and impaired liver function or is any protocol specific AEs. | From the start of study treatment (Day 1) up to the end of Week 8 of Stage 1 | 
| Number of Participants With the Maximum Toxicity Grade for the Indicated Clinical Chemistry Parameters | Clinical chemistry parameters aspartate amino transferase (AST), alanine amino transferase (ALT), gamma glutamyl transferase (GGT), total bilirubin, albumin, alkaline phosphatase, calcium, potassium, creatinine, glucose and sodium were evaluated at Baseline, at all on therapy visits, and at Week 1, Week 2, Week 3, and Week 4 visits during the follow-up period and were summarized according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 4 (NCI CTCAE V4.0): Grade 0, none; Grade 1, mild; Grade 2, moderate; Grade 3, severe or medically significant; Grade 4, life-threatening consequences; Grade 5, death related to AE. Day 1 assessment was considered as Baseline; if Day 1 was not available then Screening assessment is taken as Baseline. For creatinine, Baseline is defined as the average of Screening and Day 1 values if available and prior to first dose. Maximum post-Baseline toxicity grade included any scheduled or unscheduled post-Baseline assessment | From the start of study treatment (Day 1) up to the end of Week 6 of Stage 1 | 
| Number of Participants With the Maximum Toxicity Grade for the Indicated Hematology Parameters | Clinical hematology parameters hemoglobin, lymphocytes, platelet count, total neutrophils, white blood cell count evaluations were performed at Baseline, at all on-therapy visits, and at Week 1, Week 2, Week 3, and Week 4 visits during the follow-up period and were summarized according to the NCI CTCAE V4.0: Grade 0, none; Grade 1, mild; Grade 2, moderate; Grade 3, severe or medically significant; Grade 4, life-threatening consequences; Grade 5, death related to AE. Day 1 assessment was considered as Baseline; if Day 1 was not available then Screening assessment is taken as Baseline. Maximum post-Baseline toxicity grade included any scheduled or unscheduled post-Baseline assessment. | From the start of study treatment (Day 1) up to the end of Week 6 of Stage 1 | 
| Change From Baseline in Systolic Blood Pressure | Systolic blood pressure was measured in the sitting position at Baseline, Week 1, Week 2, Week 3, Week 4, Week 5 and Week 6. Day 1 assessment was considered as Baseline; if Day 1 was not available then the Screening assessment was considered as Baseline. Change from Baseline was calculated as the value at post-Baseline time point minus the value at Baseline. | Baseline, Week 1, Week 2, Week 3, Week 4, Week 5 and Week 6 | 
| Change From Baseline in Diastolic Blood Pressure | Diastolic blood pressure was measured in sitting position at Baseline, Week 1, Week 2, Week 3, Week 4, Week 5 and Week 6. Day 1 assessment was considered as Baseline; if Day 1 was not available then the Screening assessment was considered as Baseline. Change from Baseline was calculated as the value at post-Baseline time point minus the value at Baseline. | Baseline, Week 1, Week 2, Week 3, Week 4, Week 5 and Week 6 | 
| Change From Baseline in Pulse Rate | Pulse rate was measured at Baseline, Week 1, Week 2, Week 3, Week 4, Week 5 and Week 6. Day 1 assessment was considered as Baseline; if Day 1 was not available then the Screening assessment was considered as Baseline. Change from Baseline was calculated as the value at post-Baseline time point minus the value at Baseline. | Baseline, Week 1, Week 2, Week 3, Week 4, Week 5 and Week 6 | 
| Number of Participants With the Indicated 12-lead Electrocardiogram (ECG) Finding at Baseline | Resting 12-lead ECG was obtained at Baseline. Day 1 assessment was considered as Baseline; if Day 1 was not available then the Screening assessment was considered as Baseline. ECG was also obtained when there was clinical symptom that potentially related to cardiac dysfunction based on investigator's judgement. | Baseline | 
| Number of Participants With a Change From Baseline in Visual Acuity | Visual acuity is a measure of the spatial resolution of the visual processing system. Acuity is a measure of visual performance and is unrelated to the eyeglass prescription required to correct vision. Normal visual acuity is commonly referred to as 20/20 vision. Evaluation was done for oculus sinister (OS) for the left eye, oculus dexter (OD) for the right eye. Change from Baseline was calculated as the value at post-Baseline time point minus the value at Baseline. | From the start of study treatment (Day 1) up to the end of Week 6 of Stage 1 | 
| Number of Participants With the Indicated Grading of Myelofibrosis Using Bone Marrow Biopsy at Screening | Bone marrow biopsy was performed at Screening and then obtained when clinically indicated. Whenever a peripheral blood smear confirmed the presence of immature or dysplastic cells, a bone marrow examination was performed. Myelofibrosis (MF) was graded from Grade MF-0 to MF-3 where MF-0=scattered linear reticulin with no intersections (cross-overs) corresponding to normal bone marrow; MF-1=loose network of reticulin with many intersections; especially in perivascular areas; MF-2=diffuse and dense increase in reticulin with extensive intersections, occasionally with only focal bundles of collagen and/or focal osteosclerosis; MF-3=diffuse and dense increase in reticulin with extensive intersections with coarse bundles of collagen, often associated with significant osteosclerosis. | Screening | 
| Pharmacokinetic (PK) Assessments for Eltrombopag for Apparent Volume of Distribution of Central Compartment (Vc/F), Apparent Volume of Distribution of Peripheral Compartment (Vp/F) | Vc/F is apparent volume of distribution of plasma (VDP) in central compartment and Vp/F is apparent VDP in peripheral compartment. PK assessments were made with one group of serial sampling [Samples collected at pre-dose and 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 24 hr post-dose] and one group of sparse assessment [Samples collected at pre-dose, between 2 to 4 hr and 5 to 8 hr post-dose]. Pre-dose samples were collected within 2 hr prior to dosing, all other samples were collected within 10 minutes(min) for samples collected between 1 and 6 hrs and within 30 mins for samples collected at 8 and 24 hr. PK analysis was conducted using a population approach with non-linear mixed effects modeling methods. Point estimates of population PK parameters are presented. | From the start of study until 24 hours post-dose of Week 2 Visit of Stage 2 | 
| Pharmacokinetic Assessments for Eltrombopag for Apparent Clearance (CL/F), Apparent Inter-compartmental Clearance (Q/F) | CL/F is defined as the apparent oral clearance from plasma and Q/F is defined as apparent intercompartmental clearance. PK assessments were made with one group of serial sampling [Samples collected at pre-dose and 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 24 hr post-dose] and one group of sparse assessment [Samples collected at pre-dose, between 2 to 4 hr and 5 to 8 hr post-dose]. Pre-dose samples were collected within 2 hr prior to dosing, all other samples were collected within 10 min for samples collected between 1 and 6 hr and within 30 min for samples collected at 8 and 24 hr. PK analysis was conducted using a population approach with non-linear mixed effects modeling methods. Point estimates of population PK parameters are presented. | From the start of study until 24 hours post-dose of Week 2 Visit of Stage 2 | 
| Pharmacokinetic Assessments for Eltrombopag for Absorption Rate Constant (Ka) | Ka is defined as the absorption rate constant. PK assessments were made with one group of serial sampling [Samples collected at pre-dose and 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 24 hr post-dose] and one group of sparse assessment [Samples collected at pre-dose, between 2 to 4 hr and 5 to 8 hr post-dose]. Pre-dose samples were collected within 2 hrs prior to dosing, all other samples were collected within 10 min for samples collected between 1 and 6 hrs and within 30 mins for samples collected at 8 and 24 hr. PK analysis was conducted using a population approach with non-linear mixed effects modeling methods. Point estimates of population PK parameter is presented. | From the start of study until 24 hours post-dose of Week 2 Visit of Stage 2 | 
| Pharmacokinetic Assessments for Eltrombopag for Absorption Lag Time (ALAG) | Absorption lag time (ALAG) is defined as the time taken for a drug to appear in the systemic circulation following administration. PK assessments were made with one group of serial sampling [Samples collected at pre-dose and 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 24 hr post-dose] and one group of sparse assessment [Samples collected at pre-dose, between 2 to 4 hrs and 5 to 8 hrs post-dose]. Pre-dose samples were collected within 2 hrs prior to dosing, all other samples were collected within 10 min for samples collected between 1 and 6 hr and within 30 min for samples collected at 8 and 24 hr. PK analysis was conducted using a population approach with non-linear mixed effects modeling methods. Point estimates of population PK parameter is presented. | From the start of study until 24 hours post-dose of Week 2 Visit of Stage 2 | 
| Post-hoc Estimates of Plasma Eltrombopag Area Under the Concentration-time Curve Over a Dosing Interval (AUC[0-tau]) After 50 mg Once Daily Dose of Eltrombopag | AUC[0-tau] is defined as area under the concentration-time curve over a dosing interval (24 hr) of Eltrombopag atsteady-state after 50 mg once daily dose of eltrombopag. PK analysis was conducted using a population approach with non-linear mixed effects modeling methods. Post-hoc estimates of steady-state eltrombopag was determined based on the final PK model. Individual PK parameters were derived from the final PK model by an empirical Bayes estimation. Summary of steady-state AUC(0-tau) of eltrombopag is presented here. | From the start of study until 24 hours post-dose of Week 2 Visit of Stage 2 | 
| Post-hoc Estimates of Maximum Observed Concentration (Cmax) for Eltrombopag After 50 mg Once Daily Dose of Eltrombopag | Cmax is defined as maximum observed concentration after 50 mg once daily dose of eltrombopag. PK analysis was conducted using a population approach with non-linear mixed effects modeling methods. Post-hoc estimates of steady-state eltrombopag Cmax was determined based on the final PK model. Individual PK parameters were derived from the final PK model by an empirical Bayes estimation. Summary of steady-state Cmax of eltrombopag .is presented here. | From the start of study until 24 hours post-dose of Week 2 Visit of Stage 2 | 
| Percentage of Participants Estimated as Responders to Eltrombopag by the Pharmacokinetic/ Pharmacodynamic Model | Responders are participants whose SLOP estimates are larger than zero. The Pharmacokinetic/ Pharmacodynamic relationship between eltrombopag concentrations and the platelet response was described by a four-compartment life span model, representing one precursor production compartment, two transit/maturation compartments and one blood platelet compartment. | From the start of study until 24 hours post-dose of Week 2 Visit of Stage 2 | 
| Pharmacodynamic Parameter-Linear Proportionality Constant of Drug Effect (SLOP): the Proportional Increase of Platelet Production Rate With Each 1-μg/mL Increase in Eltrombopag Plasma Concentration | The Pharmacokinetic/ Pharmacodynamic relationship between eltrombopag concentrations and the platelet response was described by a four-compartment life span model, representing one precursor production compartment, two transit/maturation compartments and one blood platelet compartment. | From the start of study until 24 hours post-dose of Week 2 Visit of Stage 2 | 
| Pharmacodynamic Parameter- Production Rate of Platelet Precursors (KIN) | The Pharmacokinetic/ Pharmacodynamic relationship between eltrombopag concentrations and the platelet response was described by a four-compartment life span model, representing one precursor production compartment, two transit/maturation compartments and one blood platelet compartment. The estimate of KIN was fixed to 1.43x10^9/L.hr. | From the start of study until 24 hours post-dose of Week 2 Visit of Stage 2 | 
| Pharmacodynamic Parameter-Maturation Rate of Platelet Precursors (KOUT) | The Pharmacokinetic/ Pharmacodynamic relationship between eltrombopag concentrations and the platelet response was described by a four-compartment life span model, representing one precursor production compartment, two transit/maturation compartments and one blood platelet compartment. The estimate of KOUT was fixed to 0.0253 /hr. | From the start of study until 24 hours post-dose of Week 2 Visit of Stage 2 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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eltrombopag, TPO-R agonist, Chronic ITP, ETB115, Chinese chronic ITP patients