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Study of Everolimus and Mycophenolate Mofetil to Reduce Cytomegalovirus Viral Load in Solid Organ Transplant Recipients

Verified siteRegistered drugNo placebo
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What is this trial about?

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

Cytomegalovirus infection is a viral illness that can become serious in people who have received a solid-organ transplant, because their immune system is intentionally weakened to prevent organ rejection. In this situation the virus can multiply in the blood, a measurement known as viral load. The trial compares two ways of adjusting the medicines that suppress the immune system: either cutting the dose of mycophenolate mofetil in half or replacing it with the drug everolimus, while participants continue to take the usual antiviral medication that fights the virus.

The purpose of the study is to see if this immune modulation approach lowers the amount of virus in the blood compared with keeping the standard drug regimen. Participants will be assigned to one of the two adjustment strategies or to continue their current treatment, and their virus levels will be checked at the start and again after a few weeks. Additional blood tests will look at how the immune system responds to the virus, and the data will help determine whether the new strategies are effective.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Join the trial

    After providing consent, you become a participant in the horus‑cmv open proof‑of‑concept exploratory trial.

  2. Step 2

    Baseline assessment

    On the first day, blood is drawn to measure the amount of cmv virus and to assess immune markers.

    Your current medication list is recorded and any required antiviral therapy is continued.

  3. Step 3

    Randomization to treatment group

    Based on a computer system, you are assigned to one of three groups: continue usual medication, receive a reduced dose of mycophenolate mofetil, or switch to everolimus.

  4. Step 4

    Start of study medication

    If you remain on the usual regimen, you continue taking mycophenolate mofetil 3000 mg taken by mouth each day.

    If you are in the reduced‑dose arm, you take mycophenolate mofetil 1500 mg (half of the usual dose) each day.

    If you are in the everolimus arm, you stop mycophenolate mofetil and begin everolimus 3 mg taken by mouth each day.

    The assigned medication is taken daily for the entire study period.

  5. Step 5

    Regular monitoring visits

    You attend clinic visits each week for the first three weeks.

    At each visit a blood sample is taken to check the cmv viral load and to monitor safety.

    The study team may adjust other medicines if needed, but the study medication dose remains the same.

  6. Step 6

    Week 3 evaluation

    At the end of week 3 a final blood test measures the change in cmv viral load compared with the baseline value.

    The results are used to determine the primary outcome of the trial.

  7. Step 7

    Continued follow‑up

    After week 3 you continue to take the assigned medication and attend any additional visits required by the protocol until the trial ends.

    Final assessments are performed at the study’s scheduled end date.

Who can join the trial?

3 criteria

  • Clinically stable adult patients (age 18 or older) who have received a solid organ transplant such as a kidney, liver, heart, lung, or pancreas, and who now have a significant cytomegalovirus (CMV) infection confirmed by a positive CMV PCR test. CMV PCR is a laboratory test that looks for the virus’s genetic material in the blood.
  • Currently taking a maintenance immunosuppressive regimen that includes tacrolimus and mycophenolic acid (MPA), with or without steroids. Tacrolimus and MPA are medicines that help prevent the body from rejecting the transplanted organ, and steroids are anti‑inflammatory drugs sometimes used for the same purpose.
  • Has signed an informed consent form agreeing to take part in the study.

Who cannot join the trial?

5 criteria

  • Having an active acute graft rejection (your body attacking the transplanted organ) or a serious graft dysfunction (the transplanted organ not working well) that would require your doctor to change the current immune‑suppressing medicines.
  • Having taken more than 72 hours (three days) of antiviral therapy for the CMV infection before joining the study, including medicines such as valganciclovir or IV ganciclovir (ganciclovir given through a vein).
  • Being known to have an intolerance or an allergic reaction (hypersensitivity) to mTOR inhibitors (a group of drugs that lower immune activity) or to any ingredient in the drug everolimus.
  • Having any medical condition that makes using everolimus unsafe (contraindication) according to your doctor’s judgment.
  • For study sites in France only: not being part of the French social security system (no health coverage) or being under legal protection such as guardianship or curatorship (someone else makes legal decisions for you).
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Investigated drugs

  • Everolimus

    is a pill taken by mouth that helps control the immune system. In this study, it is being tested as an alternative to the usual medicines that suppress immunity after a transplant. Researchers want to see if using everolimus can lower the amount of cytomegalovirus (CMV) in the blood, because a less active immune system can sometimes let the virus grow. Participants who receive everolimus will continue their antiviral treatment, and the trial will compare how well their virus levels improve compared with those staying on the standard regimen.

  • Mycophenolate mofetil

    (listed in the trial as Mycophenolic Acid) is a medication taken by mouth that also weakens the immune system to prevent organ rejection. In this trial, patients will keep taking mycophenolate mofetil but at a reduced dose—about half of their usual amount. The goal is to find out whether lowering the dose can still protect the transplanted organ while also reducing the amount of CMV virus in the body. Like the other group, these participants will also receive antiviral therapy, and their virus levels will be compared to those who do not change their medication.

What is already known about the treatment

  • Everolimus

    This medication is taken by mouth as a tablet and is approved for use as an immunosuppressant to help prevent organ rejection and to treat certain cancers. It is a well‑studied drug that is widely available and referenced in current medical literature. Everolimus works by blocking the mTOR protein, which reduces the activity and growth of immune cells that could attack a transplanted organ. It belongs to the class of mTOR inhibitors, a type of immunosuppressive agent.

  • Mycophenolate mofetil

    This drug is taken orally in capsule form and is a standard immunosuppressant used to prevent rejection in kidney, heart and liver transplant patients. It is an established medication with extensive documentation in medical research and practice. Mycophenolate mofetil blocks the enzyme IMP dehydrogenase, lowering the building blocks needed for DNA in certain immune cells, thereby slowing their multiplication. It is classified as an antimetabolite immunosuppressant.

Investigated diseases

Cytomegalovirus infection in solid organ transplant recipients - Cytomegalovirus infection in solid organ transplant recipients is a viral illness that occurs when the CMV virus reactivates or is newly acquired after transplantation. Because the immune system is suppressed to prevent organ rejection, the virus can replicate more easily. The infection often begins with mild fever, fatigue, and low white‑blood‑cell counts, and may spread to the gastrointestinal tract, lungs, or eyes. As the viral load increases, symptoms can become more pronounced, including diarrhea, cough, or visual disturbances. Without control, the virus can cause ongoing inflammation that may affect the transplanted organ and other body systems.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-524845-28-00Protocol codeHORUS-COPEEstimated enrolment100 patientsSponsorCentre Hospitalier Universitaire Vaudois

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