Skip to content
Clinical Trials – home

Rare diseases

Investigational molecules

Locations

Our offerNewsroom

Not recruiting

Study on Prenatal Treatment of Congenital Cytomegalovirus Infection with Letermovir and Valaciclovir for Pregnant Women with CMV-Infected Fetuses

Verified siteRegistered drug
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

What is this trial about?

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

This clinical trial is focused on the prenatal treatment of congenital cytomegalovirus (CMV) infection, a virus disease that can affect unborn babies. The study is comparing two treatments: Letermovir and Valaciclovir. Letermovir, also known by its code name MK-8228, is being tested to see if it can effectively transfer from the mother to the fetus during the second trimester of pregnancy and accumulate in the amniotic fluid and placenta. Valaciclovir is a medication commonly used to treat viral infections.

The purpose of the study is to determine if Letermovir can increase the chances of a newborn having a negative CMV test at birth compared to Valaciclovir. The study will involve pregnant women who have a CMV infection in the first trimester and are carrying a fetus infected with CMV. Participants will receive either Letermovir or Valaciclovir, and the effects on the fetus and newborn will be monitored. The study will also look at the overall health and development of the newborns, as well as the safety and tolerance of the treatments for both mothers and babies.

Throughout the study, participants will undergo regular check-ups, including ultrasound scans and MRI to monitor the baby's development. The study aims to provide valuable information on the effectiveness and safety of Letermovir as a treatment option for congenital CMV infection, potentially offering a new approach to managing this condition in the future.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial assessment

    Upon joining the study, the initial assessment involves confirming eligibility criteria. This includes being a pregnant woman aged 18 or older, in the second trimester, and meeting specific medical conditions related to cytomegalovirus (CMV) infection.

    Consent for participation is required, and the ability to comply with study visits and procedures is assessed.

  2. Step 2

    Medication administration - step 1

    In the first step, the focus is on measuring the transfer of letermovir through the placenta during the second trimester. This involves monitoring its accumulation in the amniotic fluid and placenta.

    The primary goal is to determine the concentration of letermovir in fetal blood.

  3. Step 3

    Medication administration - step 2

    In the second step, letermovir is administered to women with a CMV-infected fetus following a maternal infection in the first trimester. The aim is to increase the number of newborns with a negative CMV test in blood collected on the first day of life or in cord blood if pregnancy is terminated.

    The alternative treatment involves valaciclovir, which is also administered orally.

  4. Step 4

    Monitoring and follow-up

    Throughout the trial, regular monitoring of the fetus and mother is conducted. This includes ultrasound evaluations and possibly magnetic resonance imaging (MRI) to observe changes in cerebral and placental features.

    The treatment's tolerance and adherence are assessed, along with the overall growth and health of the neonate.

  5. Step 5

    Completion and evaluation

    The trial aims to conclude by November 2026. Upon completion, the primary endpoint is a negative CMV test in neonatal blood.

    Secondary outcomes include the proportion of asymptomatic neonates, long-term health effects, and the evolution of ultrasound features over the treatment period.

Who can join the trial?

10 criteria

  • Pregnant woman who is 18 years old or older.
  • In her second trimester of pregnancy, which means she is between the 13th and 26th week of pregnancy.
  • Undergoing termination of pregnancy (TOP) for any fetal abnormality. This means the pregnancy is being ended due to issues with the fetus.
  • No evidence of placental dysfunction, meaning the placenta is working properly.
  • Affiliated with a social security regime or health insurance.
  • Has given consent to participate in the study, meaning she agrees to be part of it.
  • Must be able and willing to comply with study visits and procedures, meaning she can attend appointments and follow the study's requirements.
  • For Step 2, the woman must have had a CMV infection in the first trimester, which is the first 12 weeks of pregnancy.
  • Has a fetus that is infected with CMV between 15 and 28 weeks of pregnancy, confirmed by a positive CMV PCR test in the amniotic fluid.
  • The fetus must not have any severe cerebral ultrasound features, which are specific brain abnormalities seen on an ultrasound.

Who cannot join the trial?

6 criteria

  • Patients who are not pregnant women.
  • Patients who are not in their second trimester of pregnancy.
  • Patients who do not have a fetus infected with **CMV**. **CMV** stands for **Cytomegalovirus**, which is a type of virus.
  • Patients who have not had a **CMV** infection during the first trimester of pregnancy.
  • Patients who are male, as the study is only for female participants.
  • Patients who are considered part of a vulnerable population, which means they might need special protection or care.
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.

We usually reply within a few days

Verified sites

All sites with verified contact details – recruitment status may not be available; ask directly

Trial locations

Where you can join this trial

Countries are shaded by recruitment status. Click a recruiting country to ask about joining there.

Not recruiting
Not finding your country?

Not sure what to do next?

Joining a clinical trial can seem overwhelming. We guide you step by step, so you know exactly what to expect and how we support you through the process.

See the full process and FAQ

Investigated drugs

  • Letermovir

    is a medication being studied for its ability to transfer from the mother to the fetus during pregnancy. The trial aims to see how well it moves into the amniotic fluid and placenta, and how much of it reaches the fetal blood. The goal is to determine if it can help prevent the transmission of cytomegalovirus (CMV) from the mother to the baby.

  • Valaciclovir

    is another medication being compared in this study. It is already known for its use in treating viral infections, and the trial is investigating whether it can help reduce the presence of CMV in newborns when given to pregnant women who have a CMV infection. The study compares the effectiveness of Valaciclovir to Letermovir in achieving this goal.

What is already known about the treatment

  • Letermovir

    Letermovir is administered orally and is currently being studied for its effectiveness in treating congenital cytomegalovirus (CMV) infections. It is primarily used to prevent CMV infections in patients who have undergone organ transplants. The medication works by inhibiting the CMV DNA terminase complex, which is essential for viral replication. Letermovir is classified as an antiviral medication.

  • Valaciclovir

    Valaciclovir is taken orally and is widely used in the medical field to treat various viral infections, including herpes simplex and shingles. In the context of the clinical trial, it is being compared to Letermovir for the treatment of congenital CMV infections. Valaciclovir works by converting into acyclovir in the body, which then inhibits viral DNA synthesis. It is classified as an antiviral medication.

Investigated diseases

Cytomegalovirus Infection – Cytomegalovirus (CMV) infection is caused by a common virus that can infect people of all ages. Once the virus enters the body, it remains there for life, often without causing any symptoms. However, it can become active again, especially in individuals with weakened immune systems. In pregnant women, CMV can be transmitted to the fetus, potentially leading to congenital CMV infection. This can result in a range of health issues for the newborn, including hearing loss and developmental delays. The virus is primarily spread through bodily fluids such as saliva, urine, blood, and breast milk.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-512869-14-00Protocol codeAPHP180592Estimated enrolment46 patientsSponsorAssistance Publique Hopitaux De Paris

sourced from the EU Clinical Trials Register and site verification

Want to learn more about this trial or check if you can participate?

Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.