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Long-Term Safety Study of Zigakibart in Adults with IgA Nephropathy Who Have Completed Previous Zigakibart Trials

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What is this trial about?

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

This clinical trial is studying IgA nephropathy, a kidney disease in which the immune system protein called immunoglobulin A (IgA) builds up in the kidneys and can lead to damage over time. The treatment used in the study is zigakibart, also known as Bion 1301/FUB523, given as a subcutaneous injection under the skin. The purpose of the study is to find out the long-term safety and tolerability of zigakibart in adults who have already taken part in earlier zigakibart studies.

People in the study receive zigakibart during the extension period, which means treatment continues after the earlier trial has ended. The study follows participants over time to see how they do with ongoing treatment and to collect information about side effects, blood and urine test results, and other health checks. It also looks at how the body handles the medicine and whether the immune system makes proteins that react to it.

Because this is a long-term extension study, the main focus is continued treatment and follow-up rather than changing between different medicines. The study is designed to gather more safety information while participants remain on zigakibart.

The research process

The trial runs in 4 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    <b>study start</b>

    At the start of the study, you begin the open-label extension study. Open-label means that the study treatment is known and is not hidden.

    You receive zigakibart, also called FUB523 or Bion 1301/FUB523, as a subcutaneous injection. This means it is given as an injection under the skin.

    The dose is 600 mg per injection.

    The study is designed to continue for long-term use of zigakibart, but the source text does not give an exact dosing schedule or total treatment duration beyond the study period.

  2. Step 2

    <b>during treatment</b>

    You continue receiving zigakibart 600 mg by subcutaneous injection for the study period.

    You are monitored for safety and tolerability. Safety means how well the medicine can be used without causing harmful effects. Tolerability means how well you can take the medicine without too many side effects.

    The study records any treatment-emergent adverse events, which means side effects or medical problems that start or get worse after you begin the study treatment.

    The study also records adverse events of special interest, which means certain side effects that are of special concern in this study.

    Your blood and kidney-related measurements are checked during the study, including urine protein-to-creatinine ratio (UPCR), which measures the amount of protein in your urine, and eGFR, which is an estimate of how well your kidneys are working.

    Your serum zigakibart levels are measured. Serum means the liquid part of the blood.

    Your immunoglobulin levels are measured. Immunoglobulins are proteins in the blood that help fight infection.

    The study checks for anti-drug antibodies, which are immune proteins your body may make against the study medicine.

    Your laboratory values and vital signs are monitored. Vital signs include basic body checks such as blood pressure and pulse.

  3. Step 3

    <b>week 48 assessment</b>

    By week 48, the study measures the change in UPCR from the start of the study.

    This assessment uses a 24-hour urine collection, meaning you collect all urine passed over one full day so the amount of protein can be measured.

  4. Step 4

    <b>week 96 assessment</b>

    By week 96, the study measures the change in UPCR again using 24-hour urine collection.

    By week 96, the study measures the change in eGFR from the start of this extension study.

    The study also measures the change in eGFR from the start of the earlier BEYOND parent study to week 96 of this extension study.

Who can join the trial?

3 criteria

  • Signed informed consent must be obtained before joining the study. Informed consent means the person agrees to take part after receiving and understanding the study information.
  • The participant must have completed the parent study, meaning they finished the earlier related study, whether they had the study medicine or a placebo. A placebo is a treatment with no active medicine.
  • Based on the investigator’s medical judgment, the participant should be expected to benefit from open-label treatment with zigakibart. Open-label means everyone in the study receives the study medicine, and 600 mg s.c. Q2W means 600 milligrams given under the skin every 2 weeks.

Who cannot join the trial?

17 criteria

  • They left a previous zigakibart study early for any reason.
  • They are pregnant, breastfeeding, plan to become pregnant, or plan to donate sperm during the study and for 24 weeks after the last dose.
  • They have another serious medical or mental health problem, disease, or lab result that the study doctor thinks could make long-term treatment with zigakibart unsafe or not suitable.
  • They have a confirmed IgG level below 3 g/L before the first study treatment. IgG is a type of antibody, which is a protein that helps fight infection.
  • They are a woman who can become pregnant and are not using a highly effective form of birth control during the study and for 24 weeks after stopping treatment.
  • They are a sexually active male and are not willing to use highly effective birth control during intercourse during the study and for 24 weeks after stopping treatment.
  • They plan to donate sperm during the study or for 24 weeks after the last dose.
  • They are on chronic dialysis for at least 30 days, meaning regular machine treatment that does some of the work of the kidneys, or they need a kidney transplant.
  • They had acute kidney injury within 4 weeks before the first study treatment. Acute kidney injury means a sudden decline in kidney function.
  • They have signs or a diagnosis of rapidly progressive glomerulonephritis or another kidney filtering disease at the time of the first study treatment. This means a kidney condition that is getting worse quickly.
  • They received a live vaccine within 12 weeks before the first study treatment, or they plan to receive a live vaccine within 6 months after the last dose. A live vaccine contains a weakened germ.
  • They used systemic corticosteroids such as budesonide or other immunosuppressive medicines for more than 2 weeks during the 12 weeks before the first study treatment. Immunosuppressive medicines lower the activity of the immune system. This also includes certain listed herbs.
  • They used rituximab within 180 days before the first study treatment.
  • They have a current severe infection at the time of the first study treatment.
  • They have a history of repeated severe infections if the study doctor considers this a problem.
  • They have newly found positive tests for hepatitis A IgM antibodies, hepatitis B surface antigen, detectable hepatitis B virus DNA, hepatitis C antibodies, or HIV-1/HIV-2 antibodies. Antibodies are proteins made by the body in response to an infection.
  • They have a newly diagnosed cancer, except for certain low-risk or fully treated cancers that are allowed in the study.
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Investigated drugs

Zigakibart is the study medicine being tested in this trial. It is given as a shot under the skin. The study is checking how safe it is to use over a long period of time and how well people can tolerate it. This means the researchers want to see whether it causes any important side effects and whether participants can keep taking it without major problems. It is being studied in adults with primary IgA nephropathy, a kidney disease.

What is already known about the treatment

Zigakibart - Zigakibart is given as a solution for subcutaneous injection, which means it is injected under the skin, usually by a healthcare professional or sometimes by a trained patient. It is still an investigational medicine in clinical studies and is not yet a widely established treatment in routine medical practice, so much of its medical use is being defined by ongoing research. It is being studied for primary IgA nephropathy, a kidney disease in which the immune system plays a key role, and it is designed to reduce harmful immune activity that can damage the kidneys. Zigakibart is a monoclonal antibody, a type of targeted biologic medicine that binds to a specific protein in the immune system to help block signals that drive inflammation and disease.

Investigated diseases

IgA nephropathy - IgA nephropathy is a kidney disease in which a protein called IgA builds up in the kidneys and causes inflammation. Over time, this inflammation can lead to scarring and a gradual decline in kidney function. It may begin with blood or protein in the urine and can progress slowly over many years.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-519638-22-00Protocol codeCFUB523A12302BEstimated enrolment220 patientsSponsorNovartis Pharma AG

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