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Frexalimab versus Tacrolimus for Prevention of Kidney Transplant Rejection in Adult Kidney Transplant Recipients

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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 kidney transplant rejection, which means the body attacks a new kidney after transplantation. The study is comparing frexalimab with tacrolimus, a medicine commonly used to lower the body’s immune response after a transplant. The purpose of the study is to see whether frexalimab can work at least as well as tacrolimus in helping prevent rejection of the transplanted kidney.

Adults who have had a kidney transplant are assigned to one of the study treatments. The study is randomized, which means the treatment is chosen by chance, and open-label, which means the treatment is known to the doctors and the participants. Frexalimab is given as an injection, while tacrolimus is taken by mouth as a capsule. The study follows participants for several years after transplantation to observe how the kidney is doing and to watch for signs of rejection, graft loss, death, and side effects.

During the study, regular checkups are done to monitor kidney function, general health, and possible unwanted effects of treatment. The study also looks at new health problems that can happen after a transplant, such as high blood pressure, abnormal blood fats, and diabetes. eGFR is one of the kidney tests used in the study; it is an estimate of how well the kidney is filtering the blood.

The research process

The trial runs in 8 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    1. start of study treatment

    When you join the study, you begin treatment after kidney transplantation. The study compares frexalimab with tacrolimus to prevent kidney graft rejection, which means the body attacking the new kidney.

    You receive one of the study treatments as directed by the trial plan. Frexalimab is given as an injection. The source information does not specify the dose, how often it is given, or how long it is given. Tacrolimus is taken by mouth as hard capsules. The listed capsule strengths are 0.5 mg, 1 mg, and 5 mg. The source information does not specify the exact total daily dose, how often it is taken, or how long it is given.

  2. Step 2

    2. first 6 months after kidney transplantation

    During the first 6 months after kidney transplantation, your health is checked for signs of graft rejection, graft loss, and death. The study also measures kidney function, which is how well the kidney is working.

    At Month 1, Month 2, Month 3, Month 4, Month 5, and Month 6, the side effects of the anti-rejection treatment are assessed using the MTSOSD-59R score. This is a study score used to measure side effects of medicine that lowers the immune response.

    During this period, the study also checks for side effects, safety problems, blood pressure, cholesterol and other blood fat levels, and new diabetes after transplantation.

  3. Step 3

    3. 1 year after kidney transplantation

    At 1 year after kidney transplantation, the main study result is measured. This is called the composite efficacy failure rate, which combines biopsy-proven acute rejection (a rejection episode confirmed by a tissue sample), graft loss, and death.

    At this time point, the study also measures kidney function using eGFR, which means estimated glomerular filtration rate, a number that shows how well the kidney is filtering blood.

    The study also checks for proteinuria (protein in the urine), the iBox score, new donor-specific antibodies, and signs of rejection.

  4. Step 4

    4. 2 years after kidney transplantation

    At 2 years after kidney transplantation, the study again checks kidney function using eGFR.

    The study also measures proteinuria, graft survival, participant survival, graft rejection, and rejection episodes that have resolved.

    The study continues to monitor side effects, blood pressure, cholesterol and other blood fat levels, and the presence of new donor-specific antibodies.

  5. Step 5

    5. 3 years after kidney transplantation

    At 3 years after kidney transplantation, the study again checks eGFR, proteinuria, graft survival, participant survival, graft rejection, and rejection episodes that have resolved.

    The study also continues to monitor side effects of treatment, blood pressure, cholesterol and other blood fat levels, and other safety findings during the study period.

  6. Step 6

    6. 4 years after kidney transplantation

    At 4 years after kidney transplantation, the study again checks eGFR, proteinuria, graft survival, participant survival, graft rejection, and rejection episodes that have resolved.

    The study continues to assess side effects, blood pressure, cholesterol and other blood fat levels, and other safety findings during the study period.

  7. Step 7

    7. 5 years after kidney transplantation

    At 5 years after kidney transplantation, the study again checks eGFR, proteinuria, graft survival, participant survival, graft rejection, and rejection episodes that have resolved.

    The study also measures new donor-specific antibodies, which are antibodies your body may make against the transplanted kidney.

    At this time point, the study evaluates the long-term safety and effectiveness of the treatment, including side effects and overall kidney graft outcome.

  8. Step 8

    8. study period monitoring throughout follow-up

    Throughout the study period, the trial monitors adverse events (side effects or unwanted medical problems), serious adverse events, and treatment stopping because of side effects.

    The study also monitors laboratory test results, ecg (a test that records the heart’s electrical activity), and vital signs such as blood pressure and related measurements.

    If you receive frexalimab, the study measures its level in the blood over time, as well as ada (anti-drug antibodies, which are antibodies your body may form against the medicine).

    The study also tracks new-onset diabetes after kidney transplantation, hypertension, lipid-lowering treatment, and blood fat measurements including triglycerides, total cholesterol, non-hdl cholesterol, ldl cholesterol, and hdl cholesterol.

Who can join the trial?

3 criteria

  • Participants must be scheduled to receive their first kidney transplant, meaning the transplant must be planned and it must be the first time they receive a kidney transplant.
  • The new kidney must come from a living donor or a deceased donor. A living donor is a person who is alive, and a deceased donor is a person who has died and donated organs.
  • Participants must have low to moderate immunological risk. This means the body's defense system is not expected to strongly attack the new kidney, and the risk of rejection is not high.

Who cannot join the trial?

7 criteria

  • Receiving a kidney from a deceased donor who meets expanded criteria donor rules, or from a donor after cardiac death (a donor whose heart has permanently stopped).
  • Having a positive T-cell or B-cell crossmatch, or a positive virtual crossmatch at screening. A crossmatch test checks whether the donor kidney is likely to be attacked by the recipient’s immune system.
  • Receiving a kidney from an HLA-identical living-related donor (a living relative whose tissue match is the same), or having had a solid organ transplant, cell transplant, multi-organ transplant, or paired kidney transplant before or at the time of the study.
  • Having a main cause of ESKD (end-stage kidney disease, meaning kidney failure) that is idiopathic FSGS (a kidney scarring disease with no known cause), C3 glomerulopathy (a rare kidney disease caused by immune system protein buildup), lupus nephritis (kidney inflammation caused by lupus), or thrombotic microangiopathy (damage to small blood vessels with tiny clots).
  • Having signs of active or hidden TB (tuberculosis), HIV, HBV (hepatitis B virus), or HCV (hepatitis C virus) infection.
  • Having a known inherited tendency to form blood clots, called thrombophilia, or a past history of thromboembolic events (blood clots that block blood flow), or needing long-term anti-coagulation therapy (medicine that prevents blood clots).
  • Having severe other medical problems, an active infection, or a very limited expected lifespan because of another illness, when these problems usually prevent a person from having a kidney transplant.
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Investigated drugs

  • Frexalimab

    is the study medicine being tested in this trial. It is given by injection and is being compared with tacrolimus to see if it can help prevent the body from rejecting a transplanted kidney. The study is checking how well it works and how safe it is for adult kidney transplant recipients.

  • Tacrolimus

    is the comparison medicine in this trial. It is an immunosuppressant, which means it lowers the body’s immune response so the immune system is less likely to attack the new kidney. The trial uses tacrolimus as the standard treatment to compare against frexalimab and see whether frexalimab works just as well at preventing rejection.

What is already known about the treatment

  • Tacrolimus

    Tacrolimus is an oral medicine taken by mouth as hard capsules, usually swallowed with water, and it is used after kidney transplant to help prevent the body from rejecting the new kidney. It is a well-known and widely used medicine in medical practice and research, especially in transplant care. Tacrolimus belongs to the immunosuppressant group, which means it lowers immune activity; at the molecular level, it blocks a protein signal inside immune cells that is needed to turn on the body's attack response, helping protect the transplanted organ.

  • Frexalimab

    Frexalimab is a medicine given by injection, and it can be administered into a vein, under the skin, or into a muscle depending on the study plan and medical need. It is an investigational medicine in current medical research, so its full place in routine medical care is still being studied. Frexalimab is being developed to help prevent kidney transplant rejection, and it works by blocking a specific immune signal called CD40, which helps reduce immune cells' ability to attack the transplanted kidney. It is an immune-targeting biologic medicine, meaning it is made to act on a very specific part of the immune system.

Investigated diseases

Kidney transplant rejection - Kidney transplant rejection is a condition in which the immune system attacks a transplanted kidney because it recognizes the organ as foreign. It can develop soon after transplantation or later over time, and it may be sudden or gradual. The process can lead to inflammation and damage in the transplanted kidney, with worsening kidney function if the rejection continues.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IVTrial ID2025-521521-33-00Protocol codeEFC18554Estimated enrolment612 patientsSponsorSanofi-Aventis Recherche & Developpement

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