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Safety and Tolerability of Tenofovir Alafenamide Dose Escalation in Healthy Adults for Epstein‑Barr Virus Infection

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

The study focuses on infection with Epstein-Barr virus, a common virus that can cause fever, sore throat, and swollen glands, especially in young adults. Participants will receive an oral tablet called Vemlidy that contains the antiviral medicine tenofovir alafenamide. This medication is taken by mouth in a film‑coated tablet form and is being tested to see how safe it is when the dose is gradually increased.

The purpose of the study is to evaluate the safety and how well participants tolerate a step‑up dosing schedule of 25 mg, then 50 mg, and finally 100 mg of the drug. Volunteers will take the tablet at each dose level for a short period, after which they will provide saliva samples to check for the amount of virus present and have blood drawn to measure immune responses such as the number of CD4 T cells that react to the virus using a test called ELISPOT, as well as levels of specific antibodies, including IgG. The study proceeds without complex procedures, allowing participants to continue their normal daily activities while being monitored for any side effects.

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

    Baseline visit

    You attend a baseline visit after joining the study. during this visit a health professional records your medical history, performs routine laboratory tests, and collects a saliva sample to measure ebv (epstein-barr virus) levels.

    The information collected establishes a reference point for later comparisons during the trial.

  2. Step 2

    First dosing period (25 mg)

    You begin taking vemlidy 25 mg film-coated tablets, which contain the active substance tenofovir alafenamide. the tablet is taken by mouth once each day.

    The 25 mg dose is maintained for the duration specified by the study protocol, during which you continue your regular daily activities.

  3. Step 3

    First safety review

    After completing the initial 25 mg dosing period you return for a safety review visit. the purpose of this visit is to assess any adverse events (side effects) you may have experienced and to collect another saliva sample for ebv testing.

    Laboratory tests may also be repeated to monitor your health status.

  4. Step 4

    Second dosing period (50 mg)

    Following a satisfactory safety review, the dose is increased to 50 mg. this is achieved by taking two 25 mg tablets once daily by mouth.

    You continue this dose for the next scheduled period, maintaining daily dosing as instructed.

  5. Step 5

    Second safety review

    At the end of the 50 mg period you attend another safety review. the visit includes evaluation of any new or ongoing adverse events and collection of a saliva sample to assess changes in ebv shedding frequency and viral load.

    Additional laboratory assessments may be performed.

  6. Step 6

    Third dosing period (100 mg)

    If the 50 mg dose is well tolerated, the dose is escalated to 100 mg. this is accomplished by taking four 25 mg tablets once daily by mouth.

    You continue the 100 mg dose for the final dosing period as defined by the study schedule.

  7. Step 7

    Final assessment and study completion

    After the 100 mg period you attend a final assessment visit. this visit includes a comprehensive review of any adverse events, a final saliva sample to evaluate ebv shedding and viral load, and final laboratory tests.

    The study concludes for you after this visit, and all collected data are used to determine the safety and tolerability of the dose escalation regimen.

Who can join the trial?

7 criteria

  • Age between 18 and 65 years, and you can be male or female.
  • Positive blood test for EBNA1 or VCA IgG – this means a lab test shows you have antibodies (immune proteins) that indicate past infection with the Epstein‑Barr virus.
  • Kidney function test (creatinine clearance) of at least 80 mL per minute – this measures how well your kidneys filter waste; a result of 80 mL/min or higher is required.
  • You must be an EBV‑positive but otherwise healthy individual, meaning you have evidence of past Epstein‑Barr virus infection and no other significant health problems.
  • If you are a woman who could become pregnant (women of childbearing potential), you must agree to use a highly effective birth‑control method that has a failure rate of less than 1 % per year and continue using it throughout the study and for 7 days after the last dose.
  • You must be willing and able to follow all study procedures, including collecting saliva samples at home, for the entire study period.
  • Negative hepatitis B tests – you must have a negative result for hepatitis B surface antigen (HBsAg) and hepatitis B core antibody (anti‑HBc), showing you do not have hepatitis B infection.

Who cannot join the trial?

18 criteria

  • Known allergy or severe bad reaction to the study drug or any ingredient.
  • Low platelet count (less than 100 × 10⁹ per liter) – platelets help blood clot.
  • ALAT higher than normal – ALAT is a lab test that shows liver damage.
  • Blood creatinine higher than normal – creatinine shows how well the kidneys work.
  • Blood bilirubin higher than normal – bilirubin is a substance that can indicate liver problems.
  • Any other illness that could affect safety, following study rules, or the results.
  • Being in another drug study now or within the past 30 days.
  • Being pregnant or breastfeeding.
  • Having HIV infection, chronic active hepatitis, hepatitis C, or a positive hepatitis B surface antigen test.
  • Any sign of current or past hepatitis B infection (including a positive anti‑HBc test) – this could cause the virus to become active again.
  • History of pancreatitis – inflammation of the pancreas.
  • Conditions that make it hard to understand the study or follow the treatment plan.
  • Taking medicines that could interact with the study drug.
  • Having had a hematopoietic stem cell transplant – a procedure that replaces blood‑forming cells.
  • Having received any chemotherapy drugs before.
  • Low white blood cell count (less than 1.5 × 10⁹ per liter) unless it is caused by a reversible medication effect, and it must be above that level before starting the study.
  • History of liver disease.
  • History of kidney disease.
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Investigated drugs

Vemlidy is an oral tablet that contains the antiviral ingredient tenofovir alafenamide. This medicine works by blocking a virus’s ability to copy its genetic material, which can help control viral infections. In the DELTA‑EBV study, healthy volunteers take the tablet at gradually higher amounts to see if the drug is safe and how well people can tolerate it. The researchers closely watch for any side effects and overall safety as the dose is increased.

What is already known about the treatment

Vemlidy 25 mg film-coated tablets - It is taken orally as a film‑coated tablet, usually once a day. Tenofovir alafenamide is an approved medicine for chronic hepatitis B and is being studied for other viral infections such as Epstein‑Barr virus. It works by changing inside the body into a form that blocks a viral enzyme needed to copy the virus’s genetic code, which stops the virus from multiplying. It is classified as an antiviral nucleos(t)ide reverse‑transcriptase inhibitor.

Investigated diseases

Epstein-Barr virus infection - Epstein-Barr virus infection is a common viral infection caused by the Epstein-Barr virus, a member of the herpesvirus family. It typically begins with mild fever, sore throat, and swollen lymph nodes. The virus then spreads to the bloodstream and can cause the spleen and liver to enlarge. In many people the infection resolves on its own, while the virus remains dormant in the body. Reactivation may lead to occasional mild symptoms such as fatigue or low‑grade fever. The condition can be identified by the presence of the virus in saliva.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IITrial ID2025-522781-77-01Estimated enrolment45 patientsSponsorHelse Bergen HF

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