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Follow-up mezagitamab treatment for adults with chronic primary immune thrombocytopenia

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

PHASE3 · Takeda · NCT06948318

This follow-up will try giving mezagitamab longer-term to adults with chronic primary ITP who completed earlier mezagitamab studies to see if it stays safe, is tolerated, and helps maintain platelet responses.

Quick facts

PhasePHASE3
Study typeInterventional
Enrollment150 (estimated)
Ages18 Years and up
SexAll
SponsorTakeda (industry)
Drugs / interventionsmezagitamab, cyclophosphamide
Locations108 sites (Los Angeles, California and 107 other locations)
Trial IDNCT06948318 on ClinicalTrials.gov

What this trial studies

This open-label follow-up invites adults who completed earlier mezagitamab studies (TAK-079-3002 or TAK-079-1004) to receive additional mezagitamab doses when protocol criteria are met. The primary focus is on long-term safety and tolerability, with secondary assessments of sustained efficacy (platelet responses) and pharmacokinetics. Participants will attend periodic clinic visits for infusions, blood tests, and safety monitoring. Enrollment is limited to eligible completers of the listed parent trials, with TAK-079-1004 participants required to have demonstrated a prior platelet response.

Who should consider this trial

Good fit: Ideal candidates are adults who completed TAK-079-3002 or TAK-079-1004 (with the latter having shown a platelet response) and who meet the study's safety and eligibility criteria.

Not a fit: Patients with prior severe allergic reactions to mezagitamab components, recent thrombotic events or splenectomy, active HBV/HCV/HIV infection, recent malignancy, or those who did not respond in the earlier trial are unlikely to benefit or are ineligible.

Why it matters

Potential benefit: If successful, extended mezagitamab treatment could help sustain platelet counts and reduce bleeding in adults with chronic ITP while confirming long-term safety.

How similar studies have performed: Earlier phase studies of mezagitamab reported platelet responses in some participants, and this continuation enrolls those completers and responders to study longer-term outcomes.

Eligibility criteria

Show full inclusion / exclusion criteria 
* Key Inclusion Criteria:

  1\. 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:

1\. 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:

1. The participant has had any thrombotic or embolic event within 12 months before signing the ICF.
2. The participant has had a splenectomy within 3 months before signing the ICF.
3. The participant has active infection with hepatitis B virus (HBV), hepatitis C virus (HCV), or human immunodeficiency virus (HIV).
4. 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.
5. 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.
6. The participant has received anti-cluster of differentiation (CD) 20 treatment within 12 months before screening and either of the following applies:

   1. The last dose was received within 6 months before screening.
   2. 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.
7. The participant has received any monoclonal or polyclonal antibody for immunomodulation within 6 months before Visit 1.
8. The participant has been exposed to another investigational agent within 4 weeks or 5 half-lives, whichever is longer, before Visit 1.
9. 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.

11\. 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.

12\. 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.

Where this trial is running

Los Angeles, California and 107 other locations

+58 more sites — see ClinicalTrials.gov for the full list.

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Immune Thrombocytopenic Purpura, TAK-079, Immune Thrombocytopenia, Chronic Primary Immune Thrombocytopenia, Blood Platelet Disorders, Hematologic Diseases, Cytopenia, Purpura

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.