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

Amgen16 enrolled

Overview

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.

Study Type

INTERVENTIONAL

Allocation

Purpose

TREATMENT

Masking

NONE

Enrollment

Conditions

Thrombocytopenic Purpura

Interventions

RomiplostimDRUG

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.

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

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

Outcomes

Primary Outcomes

Number of Participants With Adverse Events

Time frame: From first dose through 8 weeks after last dose of study drug (11 weeks)

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

Secondary Outcomes

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)

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.

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.

Data from ClinicalTrials.gov

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