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A Follow-up Study of Mezagitamab in Adults with Chronic Primary Immune Thrombocytopenia to Evaluate Long-term Safety and Effectiveness

Verified siteInvestigationalNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study involves people with Chronic Primary Immune Thrombocytopenia, a condition where the body's defense system mistakenly attacks and destroys blood cells called platelets that help blood to clot. When platelet counts are too low, there is an increased risk of bleeding and bruising. The treatment being studied is called Mezagitamab, which is also known by its code name TAK-079, and is given as an injection under the skin using a solution for injection. This medicine is designed to help increase platelet counts in people with this condition.

The purpose of this study is to evaluate the long-term safety and how well mezagitamab works in adults who have already participated in previous studies with this medicine and completed those studies. The study will look at whether the treatment causes any unwanted effects over a longer period of time and whether it continues to help maintain platelet counts at safe levels. The study will also examine how long the positive effects on platelet counts last, whether people need fewer other medicines for their condition, and whether they need less emergency treatment for low platelet counts.

During the study, participants will receive mezagitamab through subcutaneous injection, which means the medicine is injected into the tissue just under the skin. The treatment can continue for up to 104 weeks. Throughout the study, doctors will monitor participants for any side effects and measure how the body responds to the treatment by checking platelet counts and other blood tests. The study will also check how the medicine moves through the body and whether the body develops any reaction against the medicine over time.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Entry into the continuation study

    This study is a continuation study designed for participants who have already completed one of two previous studies (TAK-079-3002 or TAK-079-1004).

    If you completed the TAK-079-1004 study, you must have shown a positive response to mezagitamab during that study. A response means that your platelet count (blood cells that help with clotting) increased as specified in that previous study.

    Before any procedures begin, you will be asked to provide written informed consent by signing and dating a consent form. This confirms that you understand the study and agree to participate.

  2. Step 2

    Treatment with mezagitamab

    You will receive mezagitamab, which is a medication given as an injection under the skin (subcutaneous injection).

    The medication is provided as a solution for injection.

    The specific dosage, frequency, and duration of your treatment will be determined based on the study protocol and your individual response to the medication.

    This is an open-label study, which means both you and your doctor will know that you are receiving mezagitamab.

  3. Step 3

    Regular monitoring and safety assessments

    Throughout the study, your health will be closely monitored to evaluate the long-term safety of mezagitamab.

    The study will track any treatment-emergent adverse events (side effects or health problems that occur during treatment) and serious adverse events (more severe health problems).

    Any side effects that lead to stopping the medication permanently will be recorded.

    Blood samples will be taken at selected times to measure the concentration of the medication in your blood (pharmacokinetic measurements).

    Your blood will also be tested to check if your body develops antibodies against the medication. Antibodies are proteins your immune system might create in response to the treatment.

  4. Step 4

    Assessment of treatment effectiveness

    The study will measure how long your platelet response lasts. This means tracking how long your platelet count remains at a satisfactory level.

    The occurrence of a complete response (when your platelet count reaches and maintains a specific target level) will be recorded.

    The study will also monitor whether you achieve remission of your immune thrombocytopenia, which means your condition improves significantly or resolves.

    If you need on-demand treatment (additional treatment courses when needed), the time between these treatment courses and the time until the first on-demand treatment will be tracked.

  5. Step 5

    Management of other medications

    If you are taking other medications for your immune thrombocytopenia (a condition where your immune system destroys platelets), any changes in the dose or frequency of these medications will be monitored throughout the study.

    The use of rescue therapy (emergency treatment to quickly increase your platelet count if needed) will be recorded.

  6. Step 6

    Continuation of study participation

    This is a long-term continuation study that is expected to run until July 2029.

    You will continue to receive treatment and monitoring according to the study schedule throughout your participation.

Who can join the trial?

4 criteria

  • You must have completed a previous clinical trial called TAK-079-3002 or TAK-079-1004. If you participated in TAK-079-1004, you must have shown a positive response to the study medication called mezagitamab, which means your platelet count (the number of blood cells that help stop bleeding) increased during that trial.
  • You must be 18 years of age or older.
  • You must have signed and dated an informed consent form, which is a document that explains the study and confirms you agree to participate, before any study procedures begin.
  • You must have provided any required privacy authorization, which is permission to use your personal health information for the study.

Who cannot join the trial?

4 criteria

  • The specific exclusion criteria (reasons why you cannot participate) have not been provided in the available study information
  • Generally, clinical trials have rules about who cannot join to keep participants safe
  • These rules may include things like other medical conditions you have, medicines you are taking, or recent treatments you have received
  • Your doctor will review all requirements with you to determine if you can safely participate in this study
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Investigated drugs

Mezagitamab is a medication given as an injection under the skin. It is being studied as a treatment for adults with a long-lasting blood disorder called chronic primary immune thrombocytopenia, which causes the body to have too few blood cells that help with clotting.

What is already known about the treatment

Mezagitamab – Mezagitamab is an investigational medication given as an injection under the skin (subcutaneous injection) that is currently being studied in clinical trials for the treatment of chronic primary immune thrombocytopenia, a condition where the immune system mistakenly destroys blood platelets leading to low platelet counts and increased bleeding risk. This medication works at the molecular level by targeting specific proteins on immune cells that are responsible for attacking and destroying platelets, helping to restore normal platelet levels in the blood. Mezagitamab belongs to a class of drugs called monoclonal antibodies, which are specially designed proteins that can precisely target and modify immune system activity.

Investigated diseases

Chronic Primary Immune Thrombocytopenia – Chronic Primary Immune Thrombocytopenia is a blood disorder where the immune system mistakenly attacks and destroys platelets, which are blood cells responsible for clotting. This condition leads to a reduced number of platelets in the bloodstream, resulting in easy bruising, prolonged bleeding from cuts, and spontaneous bleeding from gums or nose. The disorder is considered chronic when it persists for more than 12 months. In this condition, small red or purple spots called petechiae may appear on the skin due to minor bleeding under the surface. Women may experience heavier or longer menstrual periods than normal. The severity of symptoms can vary over time, with some periods showing fewer symptoms than others.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-521692-31-00Protocol codeTAK-079-3003Estimated enrolment150 patientsSponsorTakeda Development Center Americas Inc.

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