Phase 3 Study of Romiplostim Combined with Prednisolone versus Prednisolone Alone in Adults with Previously Untreated Primary Immune Thrombocytopenia (ITP)

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What is this study about?

The study focuses on adults who have been newly diagnosed with primary immune thrombocytopenia, a rare blood disorder in which the immune system destroys platelets, the cells that help blood clot. The treatments being compared are an injection called romiplostim, which stimulates the body to make more platelets, together with an oral steroid named prednisolone, versus taking the oral steroid alone.

The purpose of the study is to determine which treatment approach provides a longer-lasting increase in platelet levels. Participants are assigned by chance to one of the two treatment groups and receive the assigned medication for several weeks. Throughout the study, regular blood tests are performed to check platelet counts, and participants attend clinic visits to monitor their health and any side effects.

The study flow includes an initial screening, the start of the assigned therapy, periodic follow‑up visits for blood sampling and safety checks, and a final assessment at the end of the treatment period. Any serious or unexpected problems are recorded, and the overall safety of the medications is closely observed.

1 randomization into treatment group

after joining the study you will be assigned by chance to one of two treatment groups: the combination group or the prednisolone‑only group.

2 start oral prednisolone

you will take prednisolone tablets by mouth at a dose of 80 mg each day.

the medication is taken as directed for the period required by the study.

3 receive subcutaneous romiplostim (if assigned to combination group)

if you are in the combination group you will receive romiplostim as a subcutaneous injection.

the dose is calculated as 9999 µg per kilogram of body weight for each injection.

injections are given according to the schedule set by the study team.

4 attend scheduled study visits

you will visit the study site at the times specified in the protocol.

during each visit blood samples will be taken to measure your platelet count and other laboratory values.

the results help determine whether the treatment is working and monitor safety.

5 report symptoms and adverse events

you are asked to inform the study staff of any new symptoms, bleeding, or side effects you experience.

this information is used to assess treatment safety.

6 continue treatment until study end

you will keep taking the assigned medication(s) for the duration of the trial unless instructed otherwise.

the overall study period continues until the final assessment is completed.

Who Can Join the Study?

Signed informed consent: you must sign a consent form and agree to follow all study rules.
Age requirement: you must be at least 18 years old, or the legal adult age in your country if that age is older than 18.
Primary immune thrombocytopenia (ITP) diagnosis: you must have this condition, which means your blood has a low number of platelets that help stop bleeding, and you must not have been treated for it before.
Platelet count criteria: before any treatment, your platelet count must be less than 30 × 10⁹/L, or less than 50 × 10⁹/L if you have noticeable bleeding symptoms. (Platelets are tiny blood cells that help clot blood; normal range is about 150‑400 × 10⁹/L.)
Contraception use: you must use a reliable birth‑control method during the study treatment and for one month after the last dose.

Who Cannot Join the Study?

Having severe, life‑threatening bleeding that is not under control and not yet back to normal health before the study starts.
Having an active infection (for example, fever or sickness) that began within the last 7 days and has not been treated, unless all antibiotics are finished before the first study dose. Simple urinary‑tract infections or sore throats that are improving with treatment are allowed.
Having had a blood clot in a vein (deep‑vein thrombosis) in the past 3 months, or a clot in an artery (such as a mini‑stroke or stroke) in the past 6 months.
Having had major surgery within the last 28 days, or minor surgery within the last 3 days before the study.
Having chest pain caused by poor blood flow (symptomatic ischemia), uncontrolled irregular heartbeat (arrhythmia), or moderate to severe heart failure (NYHA class III or IV) at the start of the study.
Having high blood pressure that is not controlled before the study.
Having heart problems that are not well treated, such as weakened heart muscle (cardiomyopathy), major birth‑related heart defects, or serious heart‑block problems (second‑ or third‑degree atrioventricular block) within the past 4 months.
Having abnormal liver or kidney test results at screening, specifically:
- total bilirubin more than 1.5 times the normal upper limit,
- ALT or AST (liver enzymes) more than 3 times the normal upper limit,
- creatinine clearance less than 45 mL/min (a measure of kidney function calculated by the Cockcroft‑Gault formula).
Receiving live or weakened (live‑attenuated) vaccines within 4 weeks before the study, or planning to receive them during the study. Inactivated (killed) vaccines are allowed.
Having had the spleen removed (total splenectomy).
Having taken any treatment specifically for ITP (immune thrombocytopenia) before the study, except for emergency doses of certain steroids, IVIG, anti‑D, or platelet transfusion that follow the allowed short‑term limits.
Being allergic or intolerant to any of the study medicines or to products made from the bacterium Escherichia coli (such as some insulin types).
Having received the drug rituximab for any reason before the study.
Having taken chemotherapy drugs called alkylating agents within the last 8 weeks.
Using blood‑thinning medicines (anticoagulants) or drugs that stop platelets from working (antiplatelet therapy) at the same time.
Needing non‑steroidal anti‑inflammatory drugs (NSAIDs, like ibuprofen) within the last 7 days.
Currently taking part in another clinical trial, or having finished another trial less than 30 days (or less than five drug half‑lives, whichever is longer) ago.
Being judged unlikely to complete all required study visits and procedures.
Having any other serious health condition that the investigator thinks would make participation unsafe.
Being pregnant, breastfeeding, planning to become pregnant, or planning to donate eggs or breastfeed during the study and for one month after the last dose.
Having any other low blood cell counts (cytopenias) except iron‑deficiency anemia.
Having an autoimmune disease other than ITP.
Having a low platelet count caused by a medication (drug‑induced thrombocytopenia).
Having HIV infection (human immunodeficiency virus).
Having chronic hepatitis of any type (long‑lasting liver inflammation).
Having a current or past cancer, except cancers that were cured at least 3 years ago (no waiting period needed for basal cell skin cancer) and are considered low risk for coming back.
Having other blood‑forming (hematopoietic) disorders such as leukemia, myelodysplastic syndrome, or any known bone‑marrow stem‑cell disease.

Where you can join this trial?

Verified and Recommended Sites

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Verified Sites

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Other Sites

Site Name	City	Country
Virgen del Rocío University Hospital	Sevilla	Spain
Hospital General Universitario Gregorio Maranon	Madrid	Spain
Hospital General Universitario Morales Meseguer	Murcia	Spain
Hiiixrqn Vtnv dyrajjnx	Barcelona	Spain

Trial status

Country	Status	Recruitment Start
Spain	Not yet recruiting	30.09.2026

Trial locations

Investigated Drugs:

Prednisolone is a medication taken by mouth that belongs to a group of drugs called steroids. It works by calming down the immune system, which can help increase the number of platelets in the blood. In this study, it is used as the standard treatment to compare against the new approach.

Romiplostim is an injectable medicine that helps the bone marrow make more platelets. It is given under the skin and is being tested together with prednisolone to see if the combination works better than prednisolone alone for people with immune thrombocytopenia.

Investigated Diseases:

Immune thrombocytopenia

Primary immune thrombocytopenia – Primary immune thrombocytopenia is a disorder in which the immune system mistakenly targets and destroys platelets, the cells that help blood clot. This results in a reduced platelet count in the bloodstream. People may notice easy bruising, small red spots on the skin, or minor bleeding such as nosebleeds. The low platelet count can vary over time, with periods of worsening and improvement. In many patients the condition becomes chronic, persisting for months or years. The disease is considered primary when no other underlying cause can be identified.

Trial ID:

2026-525454-11-00

Protocol code:

20250124

Trial Phase:

Therapeutic confirmatory (Phase III)

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Phase 3 Study of Romiplostim Combined with Prednisolone versus Prednisolone Alone in Adults with Previously Untreated Primary Immune Thrombocytopenia (ITP)

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?