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NCT Number: NCT06948318

A Follow-up Study of Mezagitamab in Adults With Chronic Primary Immune Thrombocytopenia

Primary immune thrombocytopenia (ITP) is a condition where the immune system mistakenly destroys platelets, which are cells that help stop bleeding. This leads to a lower number of platelets, making it easier to bruise or bleed. The main aim of this study is to check how safe mezagitamab is and how well it is tolerated by adults with chronic primary ITP, if given over a longer time. Other aims are to learn how effective treatment with mezagitamab is and how the body processes it (called pharmacokinetics or PK) over a longer time.

Participants of the following previous mezagitamab studies will be invited to join this continuation study: TAK-079-3002 and TAK-079-1004. In this continuation study, participants will receive mezagitamab when certain protocol criteria are met.

During the study, participants will visit their study clinic several times.

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Key information

Conditions

Immune Thrombocytopenic Purpura (ITP) Autoimmune Diseases Blood Coagulation Disorders Blood Platelet Disorders Cytopenia Hematologic Diseases Hemic and Lymphatic Diseases Hemorrhage Hemorrhagic Disorders Immune System Diseases Pathologic Processes Pathological Conditions, Signs and Symptoms Purpura Purpura, Thrombocytopenic Purpura, Thrombocytopenic, Idiopathic Signs and Symptoms Skin Manifestations Thrombocytopenia Thrombotic Microangiopathies

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 3

Primary location

Canberra Hospital, Garran, Australian Capital Territory, Australia

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Who can participate

Healthy volunteers accepted: No

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

  • Key Inclusion Criteria:
  • The participant has completed TAK-079-3002 (end of trial [EOT]) or TAK-079-1004 (EOT). Participants from TAK-079-1004 must have had a response to mezagitamab as demonstrated by meeting the criteria for "platelet response" specified for that trial during either the main study or open-label extension.
  • Key Exclusion criteria:

For TAK-079-3002 participants:

  • The participant has a history of severe allergic or anaphylactic reactions to recombinant proteins or excipients used in the mezagitamab formulation.

For TAK-079-1004 participants:

  • The participant has had any thrombotic or embolic event within 12 months before signing the ICF.
  • The participant has had a splenectomy within 3 months before signing the ICF.
  • The participant has active infection with hepatitis B virus (HBV), hepatitis C virus (HCV), or human immunodeficiency virus (HIV).
  • History of malignancy (including myelodysplastic syndrome) within 5 years of signing the ICF, except for treated non-melanoma skin cancer or cervical carcinoma in situ.
  • In the opinion of the investigator, the participant has a serious medical or psychiatric illness that could potentially interfere with the completion of treatment according to this protocol.
  • The participant has received anti-cluster of differentiation (CD) 20 treatment within 12 months before screening and either of the following applies:
  • The last dose was received within 6 months before screening.
  • The last dose was received between 6 and 12 months before screening and the participant has a CD19+ count below the lower limit of normal.
  • The participant has received any monoclonal or polyclonal antibody for immunomodulation within 6 months before Visit 1.
  • The participant has been exposed to another investigational agent within 4 weeks or 5 half-lives, whichever is longer, before Visit 1.
  • The participant has used anticoagulants (for example, vitamin K antagonists, direct oral anticoagulants) within 3 weeks prior to Visit 1.

10 The participant has received a live or live-attenuated vaccine within 4 weeks prior to the first dose of trial treatment or has any live or live-attenuated vaccine planned during the trial.

  • The participant has used the following immunosuppressive agents as specified prior to Visit 1: alkylating agents (for example, cyclophosphamide) within 8 weeks, vinca alkaloids (for example, vincristine) within 4 weeks, sulfones (for example, dapsone) within 3 weeks, antiproliferative agents: (for example, mycophenolate mofetil and azathioprine) within 2 weeks, and calcineurin inhibitors: (for example, cyclosporine) within 2 weeks.
  • The participant has a history of severe allergic or anaphylactic reactions to recombinant proteins or excipients used in the mezagitamab formulation.

Other protocol defined inclusion/exclusion criteria may apply.

Treatment and study plan

Mezagitamab

Drug

Mezagitamab injection administered SC.

Other names: TAK-079

Primary outcomes

  1. Number of Participants With Treatment-Emergent Adverse Events (TEAEs) and Serious TEAEs

    Time frame: Up to approximately 108 weeks

    An adverse event (AE) is any untoward medical occurrence in a clinical trial participant, temporally associated with the use of the trial intervention, whether or not the occurrence is considered related to the trial intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of the trial intervention. TEAEs are defined as AEs with start dates at the time of or following the first exposure to mezagitamab in the parent trial for Cohort 1 and in this trial for Cohort 2. A serious TEAE is a TEAE that meets 1 or more of the criteria: results in death, is life threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect or was otherwise considered medically important.

  2. Number of Participants With TEAEs Leading to Permanent Withdrawal of Mezagitamab

    Time frame: Up to approximately 108 weeks

    An AE is any untoward medical occurrence in a clinical trial participant, temporally associated with the use of the trial intervention, whether or not the occurrence is considered related to the trial intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of the trial intervention. TEAEs are defined as AEs with start dates at the time of or following the first exposure to mezagitamab in the parent trial for Cohort 1 and in this trial for Cohort 2.

Secondary outcomes

  1. Duration of Platelet Response

    Time frame: Up to approximately 108 weeks

    The duration of platelet response will be measured by the cumulative number of weeks on which platelet count was ≥30,000/microliters (μL) and ≥50,000/μL throughout the trial.

  2. Duration Between On-Demand Treatment Courses

    Time frame: Up to approximately 108 weeks

  3. Time to Initiation of the First On-Demand Treatment Course

    Time frame: Up to approximately 108 weeks

  4. Number of Participants With Complete Response

    Time frame: Up to approximately 108 weeks

    Complete response is defined as achieving platelet counts ≥100,000/μL on at least 2 visits.

  5. Number of Participants With Immune Thrombocytopenia (ITP) Remission

    Time frame: Up to approximately 108 weeks

    ITP Remission is defined as all platelet counts ≥50,000/μL for at least 24 weeks after any mezagitamab treatment cycle in the absence of further therapy for ITP.

  6. Number of Participants With Reduction in Dose and/or Frequency of Concomitant ITP Medications

    Time frame: Up to approximately 108 weeks

    Concomitant ITP medications are defined as those given in addition to the trial intervention to treat your ITP. These medications include corticosteroids, thrombopoietin receptor agonists (TPO-RA), or fostamatinib.

  7. Number of Participants Requiring Rescue Therapy

    Time frame: Up to approximately 108 weeks

  8. Serum Concentrations of Mezagitamab

    Time frame: Pre-dose and at multiple time points post-dose up to Week 104

  9. Number of Participants With Anti-Drug Antibodies (ADA)

    Time frame: Pre-dose and at multiple time points post-dose up to Week 104

  10. Number of Participants With Neutralizing Antibody (NAb)

    Time frame: Pre-dose and at multiple time points post-dose up to Week 104

Study contacts

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

Takeda Contact

CONTACT

[email protected]

+1-877-825-3327

Sponsors and collaborators

Lead sponsor

Takeda

Industry

Registry information

Official study title

A Phase 3, Open-label, Multicenter Continuation Trial to Evaluate the Long-term Safety and Efficacy of Mezagitamab Subcutaneous Injection in Adults With Chronic Primary Immune Thrombocytopenia

Important dates

Study start
2025
Primary completion
2029
Study completion
2029
First posted
Apr 29, 2025
Registry last updated
Jul 10, 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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