A Study of Romiplostim Plus Predniso(lo)ne vs. Predniso(lo)ne Alone for the Treatment of Previously Untreated Primary Immune Thrombocytopenia (ITP) (ROMISTER)

July 7, 2026 updated by: Amgen

A Phase 3, Randomized, Multicenter, Open-label Study to Evaluate the Efficacy and Safety of Romiplostim Plus Predniso(lo)ne vs. Predniso(lo)ne Alone for the Treatment of Adults With Previously Untreated Primary Immune Thrombocytopenia (ITP).

This Phase 3 study is designed to evaluate the efficacy and safety of romiplostim in combination with predniso(lo)ne compared with predniso(lo)ne alone in adults with previously untreated Primary Immune Thrombocytopenia (ITP).

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

126

Phase

  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Age ≥18 years or adult legal age within country if older than 18 years.

  • Diagnosis of primary ITP according to the 2019 International Consensus (ICR) that is previously untreated and requires treatment.

    • Note: The investigator should ensure that the diagnosis of primary ITP is established by excluding other causes of isolated thrombocytopenia, as outlined in the 2019 ICR, which states that the diagnosis of primary ITP is principally based on the exclusion of other causes of isolated thrombocytopenia.
    • Note: If emergency treatment is necessary, platelet count performed before emergency can be used for study inclusion.
    • Note: Emergency ITP treatment with any thrombopoietin receptor agonists (TPO-RAs), or splenectomy is not allowed.
  • Platelet count < 30 × 10^9/L or Platelet count < 50× 10^9/L with clinically significant bleeding before any medical intervention.

Exclusion Criteria:

  • Life-threatening bleeding at randomization.
  • Known sensitivity or intolerance to any of the products to be administered during study (eg, uncontrolled diabetes) or to any Escherichia coli-derived product (eg, filgrastim, pegfilgrastim, certain insulins).
  • Uncontrolled hypertension before randomization.
  • Abnormal hepatic or renal function at screening.
  • History of total splenectomy.
  • Use of concurrent anticoagulation therapy and/or antiplatelet therapy.
  • Need for nonsteroidal anti-inflammatory drugs (NSAIDs) use and use of NSAIDs within 7 days before randomization.
  • Venous or arterial thrombotic event within 3 or 6 months, respectively, before randomization.
  • Other protocol-defined Inclusion/Exclusion may apply.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Romiplostim + Predniso(lo)ne

Participants will receive romiplostim administered subcutaneously (SC) in combination with predniso(lo)ne administered orally during Part 1 of the study.

Participants who complete Part 1 of the study will enter Part 2 and continue participation for study assessments.
Drug: Romiplostim
Administered subcutaneously.
Other Names:
  • Nplate®
  • AMG 531
Drug: Predniso(lo)ne
Administered orally.
Active Comparator: Predniso(lo)ne

Participants will receive predniso(lo)ne administered orally during Part 1 of the study.

Participants who complete Part 1 of the study will enter Part 2 and continue participation for study assessments.
Drug: Predniso(lo)ne
Administered orally.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Percentage of Participants With a Durable Platelet Response (DPR)
Time Frame: 8 weeks
8 weeks

Secondary Outcome Measures

Outcome Measure
Time Frame
Time to Next Treatment (TTNT)
Time Frame: 12 months
12 months
Cumulative Exposure to Corticosteroids
Time Frame: 12 months
12 months
Change From Baseline in ITP Patient Assessment Questionnaire (ITP-PAQ)
Time Frame: 12 months
12 months
Change in Summary Scores and Visual Analogue Scale (VAS) Scores per EuroQol 5-Dimension 5-Level (EQ 5D-5L)
Time Frame: 12 months
12 months
Incidence of Hospitalization and Rescue Medication in Part 1
Time Frame: 6 months
6 months
Number of Participants Experiencing Treatment-Emergent Adverse Events (TEAEs), Treatment-Emergent Serious Adverse Events (TESAEs), Treatment-Emergent Adverse Events of Interest (EOI), and Fatal TEAEs
Time Frame: 12 months
12 months
Percentage of Participants With Clinically Significant Bleeding Events in the Immune Thrombocytopenia-specific Bleeding Assessment Tool (ITP-BAT)
Time Frame: 6 months
6 months
Serum Trough Concentration (Ctrough) of Romiplostim
Time Frame: 6 months
6 months
Number of Participants With Anti-Romiplostim Antibodies and Anti-Thrombopoietin (TPO) Antibodies
Time Frame: 6 months
6 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Amgen

Investigators

  • Study Director: MD, Amgen

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

July 20, 2026

Primary Completion (Estimated)

September 14, 2029

Study Completion (Estimated)

September 14, 2029

Study Registration Dates

First Submitted

July 7, 2026

First Submitted That Met QC Criteria

July 7, 2026

First Posted (Actual)

July 13, 2026

Study Record Updates

Last Update Posted (Actual)

July 13, 2026

Last Update Submitted That Met QC Criteria

July 7, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 20250124

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

De-identified individual patient data for variables necessary to address the specific research question in an approved data sharing request.

IPD Sharing Time Frame

Data sharing requests relating to this study will be considered beginning 18 months after the study has ended and either 1) the product and indication have been granted marketing authorization in both the US and Europe or 2) clinical development for the product and/or indication discontinues and the data will not be submitted to regulatory authorities. There is no end date for eligibility to submit a data sharing request for this study.

IPD Sharing Access Criteria

Qualified researchers may submit a request containing the research objectives, the Amgen product(s) and Amgen study/studies in scope, endpoints/outcomes of interest, statistical analysis plan, data requirements, publication plan, and qualifications of the researcher(s). In general, Amgen does not grant external requests for individual patient data for the purpose of re-evaluating safety and efficacy issues already addressed in the product labelling. Requests are reviewed by a committee of internal advisors. If not approved, a Data Sharing Independent Review Panel will arbitrate and make the final decision. Upon approval, information necessary to address the research question will be provided under the terms of a data sharing agreement. This may include anonymized individual patient data and/or available supporting documents, containing fragments of analysis code where provided in analysis specifications. Further details are available at the URL below.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF
  • CSR

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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