Thrombocytopenic Purpura
Conditions
Keywords
Immune Thrombocytopenic Purpura, Idiopathic Thrombocytopenic Purpura, ITP, Thrombocytopenia
Brief summary
The purpose of this study is to assess the safety and tolerability of AMG 531 (romiplostim), a novel thrombopoiesis-stimulating peptibody, and its effect on platelet counts in adults with immune thrombocytopenic purpura.
Interventions
DRUGRomiplostim
Administered subcutaneously on day 1 and on day 15 or 22 if the platelet count was ≤ 50 x 10⁹/L and not rising, peak platelet count was ≤ 450 x 10⁹/L and no serious adverse events related to treatment were observed.
Sponsors
Amgen
Study design
Allocation
NA
Intervention model
SEQUENTIAL
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Greater than or equal to 3 months history of ITP, regardless of splenectomy status, and completion of at least 1 prior treatment for ITP * 2 of 3 pretreatment platelet counts that were less than 30 x 10\^9/L (if not currently on ITP therapy) or less than 50 x 10\^9/L (if currently receiving corticosteroids for ITP therapy) * Ability to give informed consent
Exclusion criteria
* Known history of arterial thrombosis, active malignancy, or bone marrow stem cell disorder
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Number of Participants With Adverse Events | From first dose through 8 weeks after last dose of study drug (11 weeks) | — |
| Number of Participants With Positive Anti-Romiplostim Antibodies | Days 29 and 78 | The presence or development of antibodies to romiplostim and endogenous thrombopoietin was assessed using a neutralizing bioassay. Antibody analyses were conducted on study days 29 and at the end-of-study visit (day 78). The number of participants with positive antibody binding at any time during the study is reported. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Number of Participants With Peak Platelet Counts of ≥ 100 x 10⁹ Cells/L | After first dose (days 3, 5, 8, 10, 12, 15, and days 17 and 19 for participants dosed on day 22), and after second dose (days 17, 19, and 22 for participants dosed on day 15, and days 24, 26, 29, 32, 36, 43, 50, 64, and 78 for all participants) | Platelet count data after the use of rescue medication were not included; participants with no platelet count data were considered non-responders. |
| Number of Participants With Peak Platelet Counts of ≥ 450 x 10⁹ Cells/L | After first dose (days 3, 5, 8, 10, 12, 15, and days 17 and 19 for participants dosed on day 22), and after second dose (days 17, 19, and 22 for participants dosed on day 15, and days 24, 26, 29, 32, 36, 43, 50, 64, and 78 for all participants) | Platelet count data after the use of rescue medication were not included; participants with no platelet count data were considered non-responders. |
| Number of Participants Who Achieved a Targeted Therapeutic Platelet Response | Baseline and after first dose (days 3, 5, 8, 10, 12, 15, and days 17 and 19 for participants dosed on day 22) and after second dose (days 17, 19, and 22 for participants dosed on day 15, and days 24, 26, 29, 32, 36, 43, 50, 64, and 78 in all participants) | Targeted therapeutic platelet response was defined as a (single) platelet count that was double the baseline level and between 50 and 450 × 10⁹ cells/L. Platelet count data after the use of rescue medication were not included; participants with no platelet count data were considered non-responders. |
| Time to Peak Platelet Count | From first dose of study drug to day 15 or 22, and from the second dose of study drug (day 15 or 22) to day 78 | Time from the date of study drug administration (day 1, 15 or 22) to the day of peak platelet count after each dose. Platelet count data after the use of rescue medication were not included. |
| Duration Within the Targeted Therapeutic Range | From first dose of study drug to day 15 or 22, and from the second dose of study drug (day 15 or 22) to day 78 | Targeted therapeutic platelet level was defined as a platelet count that was double the baseline level and between 50 and 450 × 10⁹ cells/L. Platelet count data after the use of rescue medication were not included. |
| Change From Baseline to Peak Platelet Level | Baseline and after first dose (days 3, 5, 8, 10, 12, 15, and days 17 and 19 for participants dosed on day 22) and after second dose (days 17, 19, and 22 for participants dosed on day 15, and days 24, 26, 29, 32, 36, 43, 50, 64, and 78 in all participants) | Platelet count data after the use of rescue medication were not included. |
| Number of Participants With an Increase in Platelet Count of ≥ 20 x 10⁹ Cells/L From Baseline | Baseline and after first dose (days 3, 5, 8, 10, 12, 15, and days 17 and 19 for participants dosed on day 22) and after second dose (days 17, 19, and 22 for participants dosed on day 15, and days 24, 26, 29, 32, 36, 43, 50, 64, and 78 in all participants) | Platelet count data after the use of rescue medication were not included; participants with no platelet count data were considered non-responders. |
Participant flow
Recruitment details
This was a multicenter study conducted in 6 centers in France, the Netherlands, and the United Kingdom.
Pre-assignment details
Participants were enrolled sequentially into one of four dose cohorts. When the platelet count of the first participant who received the 500 μg dose increased above 650 × 10⁹ cells/L following the first dose, this cohort was discontinued, and subsequent participants were assigned to the 300 μg cohort.
Participants by arm
| Arm | Count |
|---|---|
| Romiplostim 30 µg Participants received 30 µg romiplostim by subcutaneous injection on day 1 and a possible second dose on day 15 or 22 depending on the participant's platelet count. | 4 |
| Romiplostim 100 µg Participants received 100 µg romiplostim by subcutaneous injection on day 1 and a possible second dose on day 15 or 22 depending on the participant's platelet count. | 4 |
| Romiplostim 300 µg Participants received 300 µg romiplostim by subcutaneous injection on day 1 and a possible second dose on day 15 or 22 depending on the participant's platelet count. | 7 |
| Romiplostim 500 µg Participants received 500 µg romiplostim by subcutaneous injection on day 1 and a possible second dose on day 15 or 22 depending on the participant's platelet count. | 1 |
| Total | 16 |
Baseline characteristics
| Characteristic | Romiplostim 30 µg | Romiplostim 100 µg | Romiplostim 300 µg | Romiplostim 500 µg | Total |
|---|---|---|---|---|---|
| Age, Continuous | 60.3 years STANDARD_DEVIATION 14.9 | 37.8 years STANDARD_DEVIATION 13.4 | 53.9 years STANDARD_DEVIATION 20.4 | 45.0 years | 50.9 years STANDARD_DEVIATION 17.9 |
| Platelet Count | 13.0 10⁹cells/L STANDARD_DEVIATION 6.1 | 16.5 10⁹cells/L STANDARD_DEVIATION 10.4 | 16.4 10⁹cells/L STANDARD_DEVIATION 7.77 | 28.8 10⁹cells/L | 16.3 10⁹cells/L STANDARD_DEVIATION 8.15 |
| Race/Ethnicity, Customized Black | 0 Participants | 0 Participants | 1 Participants | 0 Participants | 1 Participants |
| Race/Ethnicity, Customized White | 4 Participants | 4 Participants | 6 Participants | 1 Participants | 15 Participants |
| Sex: Female, Male Female | 3 Participants | 2 Participants | 4 Participants | 1 Participants | 10 Participants |
| Sex: Female, Male Male | 1 Participants | 2 Participants | 3 Participants | 0 Participants | 6 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk | EG003 affected / at risk |
|---|---|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — | — / — | — / — |
| other Total, other adverse events | 4 / 4 | 4 / 4 | 7 / 7 | 1 / 1 |
| serious Total, serious adverse events | 0 / 4 | 0 / 4 | 3 / 7 | 1 / 1 |
Outcome results
Primary
Number of Participants With Adverse Events
Time frame: From first dose through 8 weeks after last dose of study drug (11 weeks)
Population: Participants who received at least 1 dose of romiplostim
| Arm | Measure | Group | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| Romiplostim 30 µg | Number of Participants With Adverse Events | Serious adverse events | 0 Participants |
| Romiplostim 30 µg | Number of Participants With Adverse Events | Serious treatment-related adverse events | 0 Participants |
| Romiplostim 30 µg | Number of Participants With Adverse Events | Discontinuations due to adverse events | 0 Participants |
| Romiplostim 30 µg | Number of Participants With Adverse Events | All adverse events | 4 Participants |
| Romiplostim 30 µg | Number of Participants With Adverse Events | Treatment-related adverse events | 1 Participants |
| Romiplostim 30 µg | Number of Participants With Adverse Events | Deaths | 0 Participants |
| Romiplostim 100 µg | Number of Participants With Adverse Events | Treatment-related adverse events | 3 Participants |
| Romiplostim 100 µg | Number of Participants With Adverse Events | Serious treatment-related adverse events | 0 Participants |
| Romiplostim 100 µg | Number of Participants With Adverse Events | Serious adverse events | 0 Participants |
| Romiplostim 100 µg | Number of Participants With Adverse Events | All adverse events | 4 Participants |
| Romiplostim 100 µg | Number of Participants With Adverse Events | Discontinuations due to adverse events | 0 Participants |
| Romiplostim 100 µg | Number of Participants With Adverse Events | Deaths | 0 Participants |
| Romiplostim 300 µg | Number of Participants With Adverse Events | Treatment-related adverse events | 3 Participants |
| Romiplostim 300 µg | Number of Participants With Adverse Events | Deaths | 0 Participants |
| Romiplostim 300 µg | Number of Participants With Adverse Events | All adverse events | 7 Participants |
| Romiplostim 300 µg | Number of Participants With Adverse Events | Serious adverse events | 3 Participants |
| Romiplostim 300 µg | Number of Participants With Adverse Events | Serious treatment-related adverse events | 1 Participants |
| Romiplostim 300 µg | Number of Participants With Adverse Events | Discontinuations due to adverse events | 0 Participants |
| Romiplostim 500 µg | Number of Participants With Adverse Events | Treatment-related adverse events | 1 Participants |
| Romiplostim 500 µg | Number of Participants With Adverse Events | Serious adverse events | 1 Participants |
| Romiplostim 500 µg | Number of Participants With Adverse Events | Deaths | 0 Participants |
| Romiplostim 500 µg | Number of Participants With Adverse Events | Discontinuations due to adverse events | 0 Participants |
| Romiplostim 500 µg | Number of Participants With Adverse Events | All adverse events | 1 Participants |
| Romiplostim 500 µg | Number of Participants With Adverse Events | Serious treatment-related adverse events | 1 Participants |
Primary
Number of Participants With Positive Anti-Romiplostim Antibodies
The presence or development of antibodies to romiplostim and endogenous thrombopoietin was assessed using a neutralizing bioassay. Antibody analyses were conducted on study days 29 and at the end-of-study visit (day 78). The number of participants with positive antibody binding at any time during the study is reported.
Time frame: Days 29 and 78
Population: Participants who received at least 1 dose of romiplostim
| Arm | Measure | Group | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| Romiplostim 30 µg | Number of Participants With Positive Anti-Romiplostim Antibodies | Anti-romiplostim antibodies | 0 Participants |
| Romiplostim 30 µg | Number of Participants With Positive Anti-Romiplostim Antibodies | Anti-thrombopoietin antibodies | 0 Participants |
| Romiplostim 100 µg | Number of Participants With Positive Anti-Romiplostim Antibodies | Anti-thrombopoietin antibodies | 0 Participants |
| Romiplostim 100 µg | Number of Participants With Positive Anti-Romiplostim Antibodies | Anti-romiplostim antibodies | 0 Participants |
| Romiplostim 300 µg | Number of Participants With Positive Anti-Romiplostim Antibodies | Anti-romiplostim antibodies | 0 Participants |
| Romiplostim 300 µg | Number of Participants With Positive Anti-Romiplostim Antibodies | Anti-thrombopoietin antibodies | 0 Participants |
| Romiplostim 500 µg | Number of Participants With Positive Anti-Romiplostim Antibodies | Anti-romiplostim antibodies | 0 Participants |
| Romiplostim 500 µg | Number of Participants With Positive Anti-Romiplostim Antibodies | Anti-thrombopoietin antibodies | 0 Participants |
Secondary
Change From Baseline to Peak Platelet Level
Platelet count data after the use of rescue medication were not included.
Time frame: Baseline and after first dose (days 3, 5, 8, 10, 12, 15, and days 17 and 19 for participants dosed on day 22) and after second dose (days 17, 19, and 22 for participants dosed on day 15, and days 24, 26, 29, 32, 36, 43, 50, 64, and 78 in all participants)
Population: Participants who received at least 1 dose of romiplostim with available data.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Romiplostim 30 µg | Change From Baseline to Peak Platelet Level | After First Dose | 38.75 10⁹ cells/L | Standard Deviation 50.5 |
| Romiplostim 30 µg | Change From Baseline to Peak Platelet Level | After Second Dose | 11.50 10⁹ cells/L | Standard Deviation 14.51 |
| Romiplostim 100 µg | Change From Baseline to Peak Platelet Level | After First Dose | 89.98 10⁹ cells/L | Standard Deviation 34.44 |
| Romiplostim 100 µg | Change From Baseline to Peak Platelet Level | After Second Dose | 46.48 10⁹ cells/L | Standard Deviation 25.15 |
| Romiplostim 300 µg | Change From Baseline to Peak Platelet Level | After Second Dose | 56.38 10⁹ cells/L | Standard Deviation 35 |
| Romiplostim 300 µg | Change From Baseline to Peak Platelet Level | After First Dose | 271.3 10⁹ cells/L | Standard Deviation 558.4 |
| Romiplostim 500 µg | Change From Baseline to Peak Platelet Level | After First Dose | 1033.20 10⁹ cells/L | — |
Secondary
Duration Within the Targeted Therapeutic Range
Targeted therapeutic platelet level was defined as a platelet count that was double the baseline level and between 50 and 450 × 10⁹ cells/L. Platelet count data after the use of rescue medication were not included.
Time frame: From first dose of study drug to day 15 or 22, and from the second dose of study drug (day 15 or 22) to day 78
Population: Participants who received at least 1 dose of romiplostim with a targeted therapeutic response.
| Arm | Measure | Group | Value (MEDIAN) |
|---|---|---|---|
| Romiplostim 30 µg | Duration Within the Targeted Therapeutic Range | After First Dose | 10.0 days |
| Romiplostim 30 µg | Duration Within the Targeted Therapeutic Range | After Second Dose | 1.0 days |
| Romiplostim 100 µg | Duration Within the Targeted Therapeutic Range | After First Dose | 5.5 days |
| Romiplostim 100 µg | Duration Within the Targeted Therapeutic Range | After Second Dose | 2.0 days |
| Romiplostim 300 µg | Duration Within the Targeted Therapeutic Range | After First Dose | 8.0 days |
| Romiplostim 300 µg | Duration Within the Targeted Therapeutic Range | After Second Dose | 8.0 days |
Secondary
Number of Participants Who Achieved a Targeted Therapeutic Platelet Response
Targeted therapeutic platelet response was defined as a (single) platelet count that was double the baseline level and between 50 and 450 × 10⁹ cells/L. Platelet count data after the use of rescue medication were not included; participants with no platelet count data were considered non-responders.
Time frame: Baseline and after first dose (days 3, 5, 8, 10, 12, 15, and days 17 and 19 for participants dosed on day 22) and after second dose (days 17, 19, and 22 for participants dosed on day 15, and days 24, 26, 29, 32, 36, 43, 50, 64, and 78 in all participants)
Population: Participants who received at least 1 dose of romiplostim.
| Arm | Measure | Group | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| Romiplostim 30 µg | Number of Participants Who Achieved a Targeted Therapeutic Platelet Response | After First Dose | 1 Participants |
| Romiplostim 30 µg | Number of Participants Who Achieved a Targeted Therapeutic Platelet Response | After Second Dose | 1 Participants |
| Romiplostim 30 µg | Number of Participants Who Achieved a Targeted Therapeutic Platelet Response | After Both Doses | 1 Participants |
| Romiplostim 100 µg | Number of Participants Who Achieved a Targeted Therapeutic Platelet Response | After Second Dose | 3 Participants |
| Romiplostim 100 µg | Number of Participants Who Achieved a Targeted Therapeutic Platelet Response | After First Dose | 4 Participants |
| Romiplostim 100 µg | Number of Participants Who Achieved a Targeted Therapeutic Platelet Response | After Both Doses | 3 Participants |
| Romiplostim 300 µg | Number of Participants Who Achieved a Targeted Therapeutic Platelet Response | After Second Dose | 3 Participants |
| Romiplostim 300 µg | Number of Participants Who Achieved a Targeted Therapeutic Platelet Response | After First Dose | 4 Participants |
| Romiplostim 300 µg | Number of Participants Who Achieved a Targeted Therapeutic Platelet Response | After Both Doses | 3 Participants |
| Romiplostim 500 µg | Number of Participants Who Achieved a Targeted Therapeutic Platelet Response | After First Dose | 0 Participants |
Secondary
Number of Participants With an Increase in Platelet Count of ≥ 20 x 10⁹ Cells/L From Baseline
Platelet count data after the use of rescue medication were not included; participants with no platelet count data were considered non-responders.
Time frame: Baseline and after first dose (days 3, 5, 8, 10, 12, 15, and days 17 and 19 for participants dosed on day 22) and after second dose (days 17, 19, and 22 for participants dosed on day 15, and days 24, 26, 29, 32, 36, 43, 50, 64, and 78 in all participants)
Population: Participants who received at least 1 dose of romiplostim.
| Arm | Measure | Group | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| Romiplostim 30 µg | Number of Participants With an Increase in Platelet Count of ≥ 20 x 10⁹ Cells/L From Baseline | After First Dose | 2 Participants |
| Romiplostim 30 µg | Number of Participants With an Increase in Platelet Count of ≥ 20 x 10⁹ Cells/L From Baseline | After Second Dose | 1 Participants |
| Romiplostim 30 µg | Number of Participants With an Increase in Platelet Count of ≥ 20 x 10⁹ Cells/L From Baseline | After Both Doses | 1 Participants |
| Romiplostim 100 µg | Number of Participants With an Increase in Platelet Count of ≥ 20 x 10⁹ Cells/L From Baseline | After Second Dose | 3 Participants |
| Romiplostim 100 µg | Number of Participants With an Increase in Platelet Count of ≥ 20 x 10⁹ Cells/L From Baseline | After First Dose | 4 Participants |
| Romiplostim 100 µg | Number of Participants With an Increase in Platelet Count of ≥ 20 x 10⁹ Cells/L From Baseline | After Both Doses | 3 Participants |
| Romiplostim 300 µg | Number of Participants With an Increase in Platelet Count of ≥ 20 x 10⁹ Cells/L From Baseline | After Second Dose | 4 Participants |
| Romiplostim 300 µg | Number of Participants With an Increase in Platelet Count of ≥ 20 x 10⁹ Cells/L From Baseline | After First Dose | 5 Participants |
| Romiplostim 300 µg | Number of Participants With an Increase in Platelet Count of ≥ 20 x 10⁹ Cells/L From Baseline | After Both Doses | 3 Participants |
| Romiplostim 500 µg | Number of Participants With an Increase in Platelet Count of ≥ 20 x 10⁹ Cells/L From Baseline | After First Dose | 1 Participants |
Secondary
Number of Participants With Peak Platelet Counts of ≥ 100 x 10⁹ Cells/L
Platelet count data after the use of rescue medication were not included; participants with no platelet count data were considered non-responders.
Time frame: After first dose (days 3, 5, 8, 10, 12, 15, and days 17 and 19 for participants dosed on day 22), and after second dose (days 17, 19, and 22 for participants dosed on day 15, and days 24, 26, 29, 32, 36, 43, 50, 64, and 78 for all participants)
Population: Participants who received at least 1 dose of romiplostim.
| Arm | Measure | Group | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| Romiplostim 30 µg | Number of Participants With Peak Platelet Counts of ≥ 100 x 10⁹ Cells/L | After First Dose | 1 Participants |
| Romiplostim 30 µg | Number of Participants With Peak Platelet Counts of ≥ 100 x 10⁹ Cells/L | After Second Dose | 0 Participants |
| Romiplostim 30 µg | Number of Participants With Peak Platelet Counts of ≥ 100 x 10⁹ Cells/L | After Both Doses | 0 Participants |
| Romiplostim 100 µg | Number of Participants With Peak Platelet Counts of ≥ 100 x 10⁹ Cells/L | After Second Dose | 1 Participants |
| Romiplostim 100 µg | Number of Participants With Peak Platelet Counts of ≥ 100 x 10⁹ Cells/L | After First Dose | 3 Participants |
| Romiplostim 100 µg | Number of Participants With Peak Platelet Counts of ≥ 100 x 10⁹ Cells/L | After Both Doses | 1 Participants |
| Romiplostim 300 µg | Number of Participants With Peak Platelet Counts of ≥ 100 x 10⁹ Cells/L | After Second Dose | 2 Participants |
| Romiplostim 300 µg | Number of Participants With Peak Platelet Counts of ≥ 100 x 10⁹ Cells/L | After First Dose | 3 Participants |
| Romiplostim 300 µg | Number of Participants With Peak Platelet Counts of ≥ 100 x 10⁹ Cells/L | After Both Doses | 1 Participants |
| Romiplostim 500 µg | Number of Participants With Peak Platelet Counts of ≥ 100 x 10⁹ Cells/L | After First Dose | 1 Participants |
Secondary
Number of Participants With Peak Platelet Counts of ≥ 450 x 10⁹ Cells/L
Platelet count data after the use of rescue medication were not included; participants with no platelet count data were considered non-responders.
Time frame: After first dose (days 3, 5, 8, 10, 12, 15, and days 17 and 19 for participants dosed on day 22), and after second dose (days 17, 19, and 22 for participants dosed on day 15, and days 24, 26, 29, 32, 36, 43, 50, 64, and 78 for all participants)
Population: Participants who received at least 1 dose of romiplostim.
| Arm | Measure | Group | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| Romiplostim 30 µg | Number of Participants With Peak Platelet Counts of ≥ 450 x 10⁹ Cells/L | After First Dose | 0 Participants |
| Romiplostim 30 µg | Number of Participants With Peak Platelet Counts of ≥ 450 x 10⁹ Cells/L | After Second Dose | 0 Participants |
| Romiplostim 30 µg | Number of Participants With Peak Platelet Counts of ≥ 450 x 10⁹ Cells/L | After Both Doses | 0 Participants |
| Romiplostim 100 µg | Number of Participants With Peak Platelet Counts of ≥ 450 x 10⁹ Cells/L | After Second Dose | 0 Participants |
| Romiplostim 100 µg | Number of Participants With Peak Platelet Counts of ≥ 450 x 10⁹ Cells/L | After First Dose | 0 Participants |
| Romiplostim 100 µg | Number of Participants With Peak Platelet Counts of ≥ 450 x 10⁹ Cells/L | After Both Doses | 0 Participants |
| Romiplostim 300 µg | Number of Participants With Peak Platelet Counts of ≥ 450 x 10⁹ Cells/L | After Second Dose | 0 Participants |
| Romiplostim 300 µg | Number of Participants With Peak Platelet Counts of ≥ 450 x 10⁹ Cells/L | After First Dose | 1 Participants |
| Romiplostim 300 µg | Number of Participants With Peak Platelet Counts of ≥ 450 x 10⁹ Cells/L | After Both Doses | 0 Participants |
| Romiplostim 500 µg | Number of Participants With Peak Platelet Counts of ≥ 450 x 10⁹ Cells/L | After First Dose | 1 Participants |
Secondary
Time to Peak Platelet Count
Time from the date of study drug administration (day 1, 15 or 22) to the day of peak platelet count after each dose. Platelet count data after the use of rescue medication were not included.
Time frame: From first dose of study drug to day 15 or 22, and from the second dose of study drug (day 15 or 22) to day 78
Population: Participants who received at least 1 dose of romiplostim with available data.
| Arm | Measure | Group | Value (MEDIAN) |
|---|---|---|---|
| Romiplostim 30 µg | Time to Peak Platelet Count | After Second Dose | 13.5 days |
| Romiplostim 30 µg | Time to Peak Platelet Count | After First Dose | 10.5 days |
| Romiplostim 100 µg | Time to Peak Platelet Count | After First Dose | 9.0 days |
| Romiplostim 100 µg | Time to Peak Platelet Count | After Second Dose | 9.5 days |
| Romiplostim 300 µg | Time to Peak Platelet Count | After First Dose | 12.0 days |
| Romiplostim 300 µg | Time to Peak Platelet Count | After Second Dose | 9.0 days |
| Romiplostim 500 µg | Time to Peak Platelet Count | After First Dose | 17.0 days |