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NCT Number: NCT07700238

A Study of Romiplostim Plus Predniso(lo)ne vs. Predniso(lo)ne Alone for the Treatment of 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).

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Key information

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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.

Treatment and study plan

Romiplostim

Drug

Administered subcutaneously.

Other names: AMG 531, Nplate®

Predniso(lo)ne

Drug

Administered orally.

Primary outcomes

  1. Percentage of Participants With a Durable Platelet Response (DPR)

    Time frame: 8 weeks

Secondary outcomes

  1. Time to Next Treatment (TTNT)

    Time frame: 12 months

  2. Cumulative Exposure to Corticosteroids

    Time frame: 12 months

  3. Change From Baseline in ITP Patient Assessment Questionnaire (ITP-PAQ)

    Time frame: 12 months

  4. Change in Summary Scores and Visual Analogue Scale (VAS) Scores per EuroQol 5-Dimension 5-Level (EQ 5D-5L)

    Time frame: 12 months

  5. Incidence of Hospitalization and Rescue Medication in Part 1

    Time frame: 6 months

  6. 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

  7. Percentage of Participants With Clinically Significant Bleeding Events in the Immune Thrombocytopenia-specific Bleeding Assessment Tool (ITP-BAT)

    Time frame: 6 months

  8. Serum Trough Concentration (Ctrough) of Romiplostim

    Time frame: 6 months

  9. Number of Participants With Anti-Romiplostim Antibodies and Anti-Thrombopoietin (TPO) Antibodies

    Time frame: 6 months

Study contacts

Contact information is provided by the study sponsor or research team.

Amgen Call Center

CONTACT

[email protected]

866-572-6436

Sponsors and collaborators

Lead sponsor

Amgen

Industry

Registry information

Official study title

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).

Acronym: ROMISTER

Important dates

Study start
2026
Primary completion
2029
Study completion
2029
First posted
Jul 13, 2026
Registry last updated
Jul 13, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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