AMIgA Study Logo
Patient Screener

Are you treating a
patient with IgA
nephropathy (IgAN)?

We are recruiting participants for the A.M.IgA. Study, a Phase 3, global, multicenter, randomized, double-blind, placebo-controlled study evaluating the efficacy and safety of mezagitamab, an investigational monoclonal antibody targeting CD38, in adults with primary IgA nephropathy (IgAN).

Do you have patients who may benefit from this study? Share the screening link to help them determine their eligibility:
Patient Screener

or email Takeda

Mezagitamab is a fully human IgG1 monoclonal antibody designed to deplete plasma cells, plasmablasts, and natural killer cells expressing CD38. Although its mechanism of action is not fully known, it is thought that by targeting these cell populations, mezagitamab may deplete the cells responsible for producing galactose-deficient IgA1 (gd‑IgA1) and autoantibodies against gd‑IgA1. Depletion of these cells is expected to decrease the formation of pathogenic gd‑IgA1 and IgA immune complexes, potentially reducing proteinuria and supporting the stabilization of renal function over time.
In a Phase 1b study, mezagitamab effectively reduced gd-IgA1, IgA, and UPCR, while preserving eGFR, up to 48 weeks. It was generally well tolerated as an add-on to standard-of-care therapy in participants with primary IgAN. The most commonly reported side effects in the study were upper respiratory tract infection, pyrexia, and oropharyngeal pain.

About the A.M.IgA. Study

Study Design and Details
  • ClinicalTrials.gov Identifier: NCT05174221
  • Recruitment Status: Active, enrolling
  • Estimated Enrollment: Up to 347 participants worldwide
  • 297 in the randomized main cohort
  • 50 in the open-label cohort for more severe disease
Screening Period
  • Up to approximately 6 weeks
  • Eligibility assessment
  • Kidney biopsy must be performed if recent medical records unavailable or if no biopsy performed within the past 10 years
Treatment Cohorts
  • Main Cohort: Randomization (2:1) to either mezagitamab or placebo
  • Open-Label Cohort: Participants not meeting main inclusion/exclusion criteria, with specific proteinuria and eGFR criteria, will receive mezagitamab
Study Treatment Periods
Two 52-week treatment periods, each consisting of:
  • 22-week dosing phase
  • Weekly subcutaneous (SC) injections for 9 doses
  • Biweekly SC injections for an additional 7 doses
  • 30-week dosing-free phase
  • Monitoring without investigational medication administration
End-of-Study Visit
  • Approximately 2 years after first dose
All participants completing the study may be eligible for a continuation study where all participants will receive mezagitamab, regardless of their assigned study treatment in the main study.
Primary Objective
To evaluate the effects of mezagitamab on proteinuria levels at Week 36 in participants who are receiving mezagitamab compared with those receiving placebo (main study only)
Primary Endpoint
Change from baseline in proteinuria at Week 36 as assessed by urine protein-to-creatinine ratio (UPCR), calculated from a 24-hour urine collection
Eligibility and Screening Requirements
  • Biopsy-confirmed primary IgAN required prior to enrollment
  • Pre-screening consent allows for 24-hour urine collection prior to full enrollment
  • Participants on a stable RAAS background therapy for at least 12 weeks
  • SGLT2 inhibitors permitted if dosing has remained stable for ≥12 weeks before informed consent
Participant Support
  • Travel assistance, meal allowances, and time reimbursement for participants/caregivers available, where permitted by local regulations
  • Use of hydroxychloroquine, herbal therapies, and traditional or complementary medicines permitted with investigator approval
  • All participants will continue taking permitted concomitant standard-of-care IgAN therapy throughout the study
Consider sharing this screening link with your patients to see if the A.M.IgA. Study might be a good fit for them:
Patient Screener

Study Design

[PLACEHOLDER FOR STUDY SCHEMATIC]

Heading...

Screening Period

  • Up to approximately 6 weeks
  • Eligibility assessment
  • Kidney biopsy may be performed if recent medical records unavailable or if no biopsy performed within 10 years

Treatment Cohorts

  • Mezagitamab Cohort: Participants receiving mezagitamab
  • Placebo Cohort: Participants receiving placebo
  • Open-Label Cohort: Participants not meeting main inclusion/exclusion criteria, including those from study TAK-079-1006 with specific proteinuria and eGFR criteria

Two 52-week treatment periods, each consisting of:

  • 22-week dosing phase
  • Weekly subcutaneous (SC) injections for 9 doses
  • Biweekly SC injections for an additional 7 doses
  • 30-week dosing-free phase
  • Monitoring without investigational medication administration

End-of-Study Visit

  • Approximately 2 years after first dose
All participants completing the study may be eligible for a continuation study.

1 https://clinicaltrials.gov/about-site/trends-charts

Eligibility Criteria

Key Inclusion Criteria

  • 18 years or older
  • Diagnosis of primary IgAN confirmed by kidney biopsy within the past 10 years (if biopsy record is unavailable, a biopsy can be completed as part of the screening activities)
  • UPCR ≥0.8 g/g or UPE ≥1 g/day, calculated from a 24-hour urine collection
  • On a stable RAAS inhibitor therapy with an ACE-I and/or ARB or ERA or MRA agent for at least 12 weeks
  • eGFR >30 mL/min/1.73m²

Inclusion Criteria for Open-Label Cohort

  • UPCR <0.8 g/g and UPE ≥0.75 and <1.0 g/day by 24-hour urine collection during the screening period and eGFR >30 mL/min/1.73m2 at screening based on the CKD-EPI formula
  • UPCR ≥0.8 g/g or UPE ≥ 1.0 g/day by 24-hour urine collection during the screening period and eGFR ≥25 and ≤30 mL/min/1.73m2 at screening based on the CKD-EPI formula

Key Exclusion Criteria

  • Secondary IgAN or other significant kidney disease
  • Rapidly progressive glomerulonephritis
  • Nephrotic syndrome
  • Recent use of immunosuppressants or biologics for immunomodulation (within 6 months)
  • Use of systemic corticosteroids at an average dose of 40 mg prednisone equivalent or higher for more than 14 days within 4 months of screening, or use of oral budesonide delayed-release capsules within 1 year of the screening visit
  • Active infection
Please note that additional criteria apply.

If you have patients who may meet these criteria, refer them to learn more and get connected with a site by sharing this screening link:

Eligibility Criteria

Key Inclusion Criteria

  • 18 years or older
  • Diagnosis of primary IgAN confirmed by kidney biopsy within the past 10 years (if biopsy record is unavailable, a biopsy can be completed as part of the screening activities)
  • UPCR ≥0.8 g/g or UPE ≥1 g/day, calculated from a 24-hour urine collection
  • On a stable RAAS inhibitor therapy with an ACE-I and/or ARB or ERA or MRA agent for at least 12 weeks
  • eGFR >30 mL/min/1.73m²

Inclusion Criteria for Open-Label Cohort

  • UPCR <0.8 g/g and UPE ≥0.75 and <1.0 g/day by 24-hour urine collection during the screening period and eGFR >30 mL/min/1.73m2 at screening based on the CKD-EPI formula
  • UPCR ≥0.8 g/g or UPE ≥ 1.0 g/day by 24-hour urine collection during the screening period and eGFR ≥25 and ≤30 mL/min/1.73m2 at screening based on the CKD-EPI formula

Key Exclusion Criteria

  • Secondary IgAN or other significant kidney disease
  • Rapidly progressive glomerulonephritis
  • Nephrotic syndrome
  • Recent use of immunosuppressants or biologics for immunomodulation (within 6 months)
  • Use of systemic corticosteroids at an average dose of 40 mg prednisone equivalent or higher for more than 14 days within 4 months of screening, or use of oral budesonide delayed-release capsules within 1 year of the screening visit
  • Active infection
Please note that additional criteria apply.

If you have patients who may meet these criteria, refer them to learn more and get connected with a site by sharing this screening link:
Patient Screener

or email Takeda

Competitive Landscape

Current treatments for IgAN include RAAS inhibitors, steroids, budesonide, SGLT2 inhibitors, and complement inhibitors, which primarily manage symptoms and slow disease progression.

Mezagitamab is a monoclonal antibody that targets CD38 on plasma cells. By depleting both short- and long-lived plasma cells, mezagitamab’s use in this study is intended to reduce the production of gd-IgA1 and autoantibodies, with the goal of addressing key factors believed to contribute to IgAN.

This approach may lead to more sustained reductions in proteinuria and help stabilize kidney function in patients with persistent proteinuria despite standard therapy.

Consider sharing this screening link with your patients to help them check their eligibility:

Phase 1b Results1

Objective

This open-label, single-arm, Phase 1b multicenter study (NCT05174221) enrolled 17 participants. All participants received SC mezagitamab 600 mg once weekly for 8 weeks, followed by 600 mg every 2 weeks for an additional 16 weeks (for a total of 16 doses). Treatment was followed by a 24-week safety follow-up period. Thirteen participants continued into a long-term extension for observation, with efficacy and safety evaluated through Week 96.

Key Efficacy Findings

Biological Activity
  • Rapid reduction from baseline through Week 96 for the following:
  • Serum Gd-IgA1 had mean decrease of 50.1%
  • Serum IgA had sustained reductions of 29.1%
  • Serum IgG had a nadir of approximately -35% at Week 12 with complete recovery at Week 96
Proteinuria
  • Mean reduction of 55.2% in 24-hour UPCR from baseline to Week 96
  • Reduction sustained throughout the dosing-free period of 18 months
Renal Function
  • eGFR remained stable, with no meaningful decline observed through Week 96
  • Resolution of hematuria in 60% of participants who had hematuria at baseline
Safety Profile
  • Mezagitamab was generally well tolerated as an add-on therapy through Week 96
  • No serious adverse events (AEs), opportunistic infections, or Grade ≥3 infections were reported
  • No study discontinuations occurred due to AEs
  • Most common treatment-emergent AEs (all mild to moderate):
  • Upper respiratory tract infection (47.1%)
  • Pyrexia (23.5%)
  • Oropharyngeal pain (23.5%)
  • No new safety concerns identified after long-term follow-up
The overall safety observations support continued clinical development of mezagitamab in IgAN.
Click to enlarge.
Reference

1 Barratt, J., Suzuki, Y., Nguyen, V. A., Dobler, I., Li, C., Patwari, P., & Farmer, M. K. (2025 November 6–9). Safety, tolerability, and efficacy of mezagitamab (TAK-079) as add-on to standard-of-care therapy in individuals with primary IgA nephropathy: week 96 data from an open-label phase 1b study. American Society of Nephrology Kidney Week 2025, Houston, TX, USA.

Refer a Patient

To learn more or refer a patient, please contact the Takeda A.M.IgA. Study team.

Each patient will be required to have a visit with a study doctor to further evaluate whether they may qualify.

Travel assistance, meal allowances, and time reimbursement for participants/caregivers may be available, where permitted by local regulations. The investigational medication, placebo, and all study-related tests will be provided at no cost to participants during their study participation.

Help your patients learn more and determine if the study might be a good fit for them by sharing the screening link below:
Patient Screener

or email Takeda

Patient Eligibility

Share the following screening link with patients to help them check their eligibility for participation:

Eligibility Criteria

Key Inclusion Criteria

  • 18 years or older
  • Diagnosis of primary IgAN confirmed by kidney biopsy within the past 10 years (if biopsy record is unavailable, a biopsy can be completed as part of the screening activities)
  • UPCR ≥0.8 g/g or UPE ≥1 g/day, calculated from a 24-hour urine collection
  • On a stable RAAS inhibitor therapy with an ACE-I and/or ARB or ERA or MRA agent for at least 12 weeks
  • eGFR >30 mL/min/1.73m²

Open-Label Cohort

  • UPCR <0.8 g/g and UPE ≥0.75 and <1.0 g/day by 24-hour urine collection during the screening period and eGFR >30 mL/min/1.73m² at screening based on the CKD-EPI formula
  • UPCR ≥0.8 g/g or UPE ≥ 1.0 g/day by 24-hour urine collection during the screening period and eGFR ≥25 and ≤30 mL/min/1.73m² at screening based on the CKD-EPI formula

Key Exclusion Criteria

  • Secondary IgAN or other significant kidney disease
  • Rapidly progressive glomerulonephritis
  • Nephrotic syndrome
  • Recent use of immunosuppressants or biologics for immunomodulation (within 6 months)
  • Use of systemic corticosteroids at an average dose of 40 mg prednisone equivalent or higher for more than 14 days within 4 months of screening, or use of oral budesonide delayed-release capsules within 1 year of the screening visit
  • Active infection
Please note that additional criteria apply.

If you have patients who may meet these criteria, refer them to check their eligibility by sharing this screening link:

Participating Research Sites

Enter your ZIP code to locate the nearest participating study site.

Address or ZIP/postal code

1 https://clinicaltrials.gov/about-site/trends-charts

Refer a Patient

Patient Screener

or email Takeda

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