Amgen Megakaryopoiesis Protein 2 (AMG 531) in Thrombocytopenic Subjects With Immune Thrombocytopenic Purpura (ITP)

Phase 1

Completed

• Conditions: Thrombocytopenic Purpura
• Interventions: Drug: Romiplostim

• Registration Number: NCT00117143
• Lead Sponsor: Amgen

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.

Detailed Description

Not available

Study Timeline

• Study Start: 2002-12-02
• Primary Completion: 2004-07-19
• Study Completion: 2004-07-19
• Study First Submitted: 2005-06-30
• Study First Submitted QC: 2005-06-30
• Study First Posted: 2005-07-04
• Results First Submitted: 2019-06-03
• Status Verified: 2019-11
• Results First Submitted QC: 2019-12-05
• Results First Posted: 2019-12-20
• Last Update Submitted: 2023-06-22
• Last Update Posted: 2023-06-26

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 16

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

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SEQUENTIAL

Arm && Interventions

Group	Intervention	Description
Romiplostim	Romiplostim	Participants will receive a maximum of 2 administrations of romiplostim by subcutaneous injection, the first on day 1 of the study and the second on day 15 or 22 depending on the participant's platelet count. Romiplostim doses to be tested were 30, 100, 300, and 500 μg.

Primary Outcome Measures

Name	Time	Method
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 Outcome Measures

Name	Time	Method
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.
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.
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.
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.
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.