Prenatal Treatment of Congenital Cytomegalovirus Infection With Letermovir Versus Valaciclovir (CYMEVAL3-step2)

March 26, 2026 updated by: Assistance Publique - Hôpitaux de Paris

Prenatal Treatment of Congenital Cytomegalovirus Infection With Letermovir Randomized Against Valaciclovir (Step 2)

The investigators' hypothesis is that maternal treatment with Letermovir will inhibit fetal CMV replication better than Valaciclovir in infected fetuses and lead to a higher proportion of negative CMV PCR at birth in neonatal blood collected in the first day of life or in cord blood in case of termination of pregnancy (TOP).

The main objective is to demonstrate that Letermovir administered to women carrying a CMV infected fetus following a maternal infection of the first trimester increases the proportion of neonates with a negative CMV PCR in neonatal blood collected in the first day of life or in cord blood in case of termination of pregnancy (TOP) compared to Valaciclovir.

In each group , the proportion of asymptomatic neonates and the number and type of long-term sequelae at 2 years will also be assessed and compared.

Study Overview

Status

Recruiting

Detailed Description

15-20% of CMV infected fetuses are symptomatic and up-to 60% of those symptomatic fetuses have postnatal sequelae. Long-term sequelae are essentially neurological deficiencies and hearing loss. Long-term sequelae are mainly seen in fetuses infected following a maternal infection in the first trimester. The physiopathology of brain and inner ear lesions is not completely elucidated but the viral lesions and viral replication play a major role in this altered neurodevelopment. Fetuses with the most severe brain lesions are also those presenting with high CMV replication in the brain and in all other organs. Moreover, placenta infection affects fetal growth causing growth restriction and therefore affects fetal development in that way. Finally, infected fetuses with high blood viral load at diagnosis (around 22 weeks) are more likely to be symptomatic at birth (OR=5.7 IC95% 2.02-16.53). This correlation between symptoms and high levels of viral replication suggests that an antiviral treatment that could efficiently inhibit viral replication could be beneficial.

Neonatal antiviral treatment with Ganciclovir or Valganciclovir has been used for more than 20 years and is recommended for infected neonates that are symptomatic. Two randomized studies demonstrated that this treatment improves hearing and intellectual capacities of symptomatic neonates with central nervous system involvement. However, this improvement is only modest. This modest benefit can probably be explained by the fact that cerebral lesions developed in utero are already fixed in the neonatal period. The investigators' hypothesis is that early prenatal antiviral therapy for infected fetuses at high risk of cerebral lesions will be more efficient to alleviate long-term sequelae than neonatal treatment. The prognosis of fetal infection can now be established upon fetal imaging by ultrasound (US) and MRI, combined with fetal laboratory tests (fetal platelets count and viral load). The prognosis is poor for severe brain lesions and good when imaging and laboratory parameters are normal. In between these extremes, symptomatic fetuses with extra-cerebral or mild cerebral features are an appropriate target for antiviral therapy with the aim to prevent the development of irreversible cerebral injury.

The 3 antiviral drugs (Ganciclovir, Foscarnet and Cidofovir) that are licensed to treat CMV infection and disease in immunosuppressed patients are nucleotide inhibitors and because of their potential carcinogenicity and teratogenicity, they should be avoided in pregnancy. Valaciclovir is efficient to prevent CMV infection in transplanted patients, is safe in pregnancy and crosses the placenta efficiently. The investigators carried a phase II, not randomized, open label clinical trial to test the efficacy of Valaciclovir in infected fetuses. Valaciclovir was given to women carrying a fetus with at least 1 non-severe ultrasound feature from prenatal diagnosis up until delivery. This led to 79% asymptomatic neonates compared to 43% following natural history of the disease. However, the efficacy of Valaciclovir seemed only partial. First, the antiviral effect was partial: although fetal blood viral load decreased with treatment, 90% of treated fetuses still had detectable CMV DNA in cord blood at birth and all had detectable CMV DNA in neonatal saliva and urine. And second, the clinical efficacy was not optimal since only 57% of fetuses with more than 1 ultrasound feature were born asymptomatic, suggestive of Valaciclovir lower efficacy in such cases.

The investigators therefore looked at new anti CMV drugs. Among them only Letermovir has been licensed to prevent CMV disease in transplanted patients in 2018 and will be available in 2019. Letermovir is not a nucleotide inhibitor and has specific anti-CMV activity. In preclinical toxicity studies it was not genotoxic, not teratogenic and did not impair fertility at the recommended human doses. Besides, no specific concern arises from its safety profile in humans. It controls CMV infection and disease in bone marrow transplant patients by achieving blood viral load clearance in 50-80% of cases.

The investigators' hypothesis is that maternal treatment with Letermovir will inhibit fetal CMV replication better than Valaciclovir in symptomatic infected fetuses and lead to a higher proportion of negative CMV PCR at birth in cord blood. Since severity is largely related to viral replication, clearance of viral replication is a valid surrogate endpoint for clinical outcome in such rare and phenotypically variable cases

The investigators' main objective is to demonstrate that Letermovir administered to women carrying a CMV infected fetus following a maternal infection of the first trimester increases the proportion of neonates with a negative CMV PCR in neonatal blood collected in the first day of life or in cord blood in case of termination of pregnancy (TOP) compared to Valaciclovir. The primary endpoint is the proportion of negative CMV PCR (<500 IU/ml) in neonatal blood collected in the first day of life or in cord blood at termination of pregnancy

The following will also to be compared between the 2 arms : the proportion of asymptomatic neonates, the overall growth, the proportion of long-term sequelae at 2 years of age, the tolerance of treatment for mothers, fetuses and neonates, the maternal adherence to treatment, the evolution of ultrasound features between Day0 and Week 2, Week 4, and Week 6 of treatment, the changes in cerebral and placental features between Day 1st magnetic resonance imaging (MRI) within the first month of inclusion and 2nd MRI at 32 ± 2 WA, the post-mortem examination in cases with medical termination of pregnancy (TOP).

Study Type

Interventional

Enrollment (Estimated)

46

Phase

  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

      • Paris, France, 75015
        • Recruiting
        • Hôpital Necker - Enfants Malades
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Pregnant woman ≥ 18 years old,
  • CMV infection in the 1st trimester
  • with an infected fetus at 15 -28 weeks (positive CMV PCR in the amniotic fluid) With a fetus presenting without any severe cerebral ultrasound feature (ventriculomegaly ≥15 mm, hydrocephalus, periventricular hyperechogenicity, microcephaly<-3SD, vermian hypoplasia, porencephaly, lissencephaly, corpus callosum dysgenesis, cystic leukomalacia)
  • affiliation to a social security regime//health insurance
  • Given consent for the study
  • Patient must be able and willing to comply with study visits and procedures

Exclusion Criteria

  • Participation to another interventional drug trial (category 1)
  • Subject protected by law under guardianship or curatorship
  • Maternal CMV infection after 15 weeks'
  • Creatinine clearance <50 ml/mn/1,73m²
  • Liver insufficiency (Child Pugh grade C), AST, ALT 5 x ULN, bilirubin 2 x ULN.
  • Woman with known allergy to Letermovir or Valaciclovir
  • Contraindication for the administration of Letermovir and Valaciclovir listed in the SmPC of Prevymis® and Zelitrex®
  • Women with hypersensitivity to aciclovir
  • Concomitant administration of St John's wort
  • Woman treated by pimozide, ergot alkaloids, dabigatran, atorvastatin, simvastatin, rosuvastatin, pitavastatin or cyclosporin.
  • Woman with hereditary intolerance to galactose, with lactose lapp deficiency, glucose or galactose malabsorption syndrome

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Letermovir
Maternal daily administration of letermovir + placebo of valaciclovir
Maternal daily administration of 240 milligrams of letermovir (1x240 mg-tablets) up-until delivery or TOP Placebo of Valaciclovir ; daily administration of 8 grams of valaciclovir (2 g (4 x500 mg-tablets) every 6 hours) up-until delivery or TOP
Active Comparator: Valaciclovir
Maternal daily administration of valaciclovir + placebo of letermovir
Maternal daily administration of 8 grams of valaciclovir (2 g (4 x500 mg-tablets) every 6 hours) up-until delivery or TOP Placebo of letermovir : (1x240 mg-tablets) up-until delivery or TOP

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
CMV PCR in neonatal blood collected
Time Frame: At Termination of pregnancy
Negative CMV PCR (<500 IU/ml) in cord blood
At Termination of pregnancy
CMV PCR in neonatal blood collected
Time Frame: in the first day of life
Negative CMV PCR (<500 IU/ml) in neonatal blood
in the first day of life

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Number of asymptomatic neonates
Time Frame: in the first day of life
in the first day of life
Birthweight
Time Frame: at birth
at birth
placental weight
Time Frame: at birth
at birth
number of long-term sequelae
Time Frame: at 2 years of life
at 2 years of life
type of long-term sequelae
Time Frame: at 2 years of life
at 2 years of life
maternal full blood count
Time Frame: up to 39 weeks
during pregnancy
up to 39 weeks
maternal renal function
Time Frame: up to 39 weeks
during pregnancy
up to 39 weeks
maternal liver function
Time Frame: up to 39 weeks
measurements of liver enzyme (ALAT ASAT GCT PAL) and bilirubin during pregnancy
up to 39 weeks
gestational age at delivery
Time Frame: at birth
at birth
neonatal defects non related to infection
Time Frame: in the first day of life
in the first day of life
changes in ultrasound features
Time Frame: up to 39 weeks
changes in ultrasound features as per 4 groups : 1) stable, 2) disappearance or decrease in symptoms, 3) increase or new non-severe symptoms 4) appearance of severe cerebral symptoms during pregnancy and at birth or the end of trial
up to 39 weeks
brain biometrics during pregnancy
Time Frame: up to 39 weeks
fetal assessment
up to 39 weeks
gyration disorders during pregnancy
Time Frame: up to 39 weeks
fetal assessment
up to 39 weeks
white matter abnormalities during pregnancy
Time Frame: up to 39 weeks
fetal assessment
up to 39 weeks
ventriculomegaly during pregnancy
Time Frame: up to 39 weeks
fetal assessment
up to 39 weeks
parenchymal abnormalities during pregnancy
Time Frame: up to 39 weeks
fetal assessment
up to 39 weeks
hepatomegaly during pregnancy
Time Frame: up to 39 weeks
fetal assessment
up to 39 weeks
splenomegaly during pregnancy
Time Frame: up to 39 weeks
fetal assessment
up to 39 weeks
intestinal abnormalities during pregnancy
Time Frame: up to 39 weeks
fetal assessment
up to 39 weeks
abnormal amniotic fluid volume during pregnancy
Time Frame: up to 39 weeks
fetal assessment
up to 39 weeks
fetal assessment
Time Frame: up to 39 weeks
Classification after pathological cerebral examination in severe and non-severe cases during pregnancy
up to 39 weeks
CMV DNA load in fetal blood
Time Frame: up to 39 weeks
in fetal blood by quantitative PCR in IU/mL
up to 39 weeks
CMV DNA load in cord blood
Time Frame: up to 39 weeks
cord blood by quantitative PCR in IU/mL
up to 39 weeks
CMV DNA load in neonatal blood
Time Frame: up to 3 days of life
neonatal blood by quantitative PCR in IU/mL
up to 3 days of life
CMV DNA load in amniotic fluid
Time Frame: up to 39 weeks
amniotic fluid by quantitative PCR in IU/mL
up to 39 weeks
CMV DNA load in saliva
Time Frame: up to 3 days of life
saliva by quantitative PCR in IU/mL during pregnancy and first days of life
up to 3 days of life
CMV DNA load in urine
Time Frame: up to 3 days of life
urine by quantitative PCR in IU/mL during pregnancy and first days of life
up to 3 days of life
Letermovir concentration in cord blood
Time Frame: at birth or TOP
in cord blood
at birth or TOP
Letermovir concentration in amniotic fluid
Time Frame: at birth or TOP
in amniotic fluid
at birth or TOP
Letermovir concentration in placenta
Time Frame: at birth or TOP
in placenta
at birth or TOP
neonatal full blood count
Time Frame: in the first day of life
in the first day of life
neonatal renal function
Time Frame: in the first day of life
in the first day of life
neonatal liver function
Time Frame: in the first day of life
in the first day of life
compliance
Time Frame: up to 39 weeks
pill count during pregnancy at each visit and at the end of the trial
up to 39 weeks
compliance
Time Frame: up to 39 weeks
valaciclovir or letermovir concentrations in maternal blood during pregnancy Every 2 follow-up visits and at birth or TOP
up to 39 weeks
changes in placental features on MRI
Time Frame: up to 39 weeks
changes in placental features on MRI, measuring placental T2 relaxation time, diffusion parameters and IVIM
up to 39 weeks
Letermovir concentration in neonatal blood
Time Frame: in the first day of life
in neonatal blood
in the first day of life
Sequencing of CMV UL56 and UL89 genes
Time Frame: in the first day of life
Sequencing of CMV UL56 and UL89 genes in positive neonates for CMV PCR
in the first day of life

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Investigators

  • Study Chair: Marianne LERUEZ-VILLE, MD, PhD, Virology laboratory- reference national Lab for CMV infection -Hôpital Necker-Enfants malades, Paris

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

October 20, 2023

Primary Completion (Estimated)

August 1, 2029

Study Completion (Estimated)

August 1, 2029

Study Registration Dates

First Submitted

June 7, 2022

First Submitted That Met QC Criteria

July 5, 2022

First Posted (Actual)

July 6, 2022

Study Record Updates

Last Update Posted (Actual)

March 31, 2026

Last Update Submitted That Met QC Criteria

March 26, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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