Prenatal Treatment of Congenital Cytomegalovirus Infection With Letermovir Randomized Against Valaciclovir - CYMEVALIII STEP1 (CYMEVAL3-STEP1)

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

Prenatal Treatment of Congenital Cytomegalovirus Infection With Letermovir Randomized Against Valaciclovir - STEP 1

In the model of the perfused cotyledon, Letermovir crosses the placenta to reach appropriate fetal concentration. The cotyledon model can only be performed in the third trimester placenta. Although it is probable that the transplacental passage in the second trimester is in the same range than the one found in the 2th trimester, it needs to be confirmed. The study will be divided in 2 steps: step 1 will study the Letermovir transplacental transfer in the second trimester and step 2 will test the efficacy of letermovir to inhibit replication in infected fetuses.

Main objective To measure the Letermovir transplacental transfer in the second trimester and its accumulation in the amniotic fluid and the placenta in the second trimester

Primary end point:

Concentrations reached in fetal blood relative to EC50 of letermovir.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

The eligible population of step 1 will be pregnant women in their second trimester of pregnancy and undergoing TOP for any fetal abnormality and no evidence of placental dysfunction.

Letermovir (LTM) is a new anti CMV drug, manufactured by Merck that:

  • is highly efficient in vitro against CMV (more than ganciclovir the gold standard drug)
  • is as efficient as valganciclovir to cure CMV infection and highly efficient as a prophylaxis to avoid CMV infection and disease in bone marrow transplated patients
  • is very well tolerated
  • has no data from the use in pregnant women and animal studies are insufficient with respect to fetotoxicity, but no specific concern in pregnant women arises from its safety profile
  • crosses the placenta in the ex vivo model of the human perfused cotyledon to reach efficient fetal concentration

In this STEP 1 study, we elected to test 2 Letermovir dosages:

  • 240 mg given orally once a day. Based on 10% rate of letermovir transplacental passage as demonstrated in the cotyledonon model, we calculated that the dosage of 240 mg given once a day to the pregnant woman should be suffisent to reach efficient concentration in fetal blood.
  • 480 mg /day given orally once a day. 480 mg per day is the recommended dose to prevent CMV infection in bone marrow transplanted patients;

The risks added by the study are those of letermovir: nausea, diarrhea and vomiting (frequent), hypersensitivity, loss of appetite, headache, vertigo, abdominal pain, ALT and AST increase, muscule spasm, blood creatinine increase, fatigue, peripheral edema (very rare). The expected benefit for the women is: none.

Women and obstetrician investigator will sign the written consent for the trial.

  • Validation of inclusion and non-inclusion criteria will be assessed by the obstetrician investigator as follows:
  • age, weight, height and medical history will be collected.
  • Inquiry on maternal concomitant treatment(s)
  • Blood sampling: (4 ml altogether)
  • 1 Heparinate Lithium tube (2 ml) for measurements of urea, creatinine, creatinine clearance, liver enzyme (ALAT ASAT GGT PAL), bilirubine
  • 1 EDTA tube of 2 ml for full blood test count These measurements will be done in the biochemistry laboratory of the investigating site.

When validation of inclusion and non-inclusion criteria is done (all the criteria will be available on the day of the baseline visit), the woman receives the tablets of letermovir. They will be allocated either 240 mg or 480 mg up until termination of pregnancy. 5 women will receive 240 mg. In order to have variation in the time elapsed between administration and sampling, it will be asked to 3 women to take the drug every morning and to 2 patients to take the drug every evening. 5 women will receive 480 mg. This time, it will be asked to 2 women to take the drug every morning and to 3 patients to take the drug every evening.

Hence, the day of TOP, patients who take the drug every evening will have the largest delay between the last intake and blood sampling. The patients who take the drug every morning should take the last tablet early in the morning the day of TOP and latest 4 hours before the blood sampling.

After the baseline visit, there will be one other visit just before TOP; the obstetrician investigator will be in charge of this visit:

  1. Maternal examination will comprise:

    • Inquiry of potential side effects (nausea, vomiting, diarrhea, rash, cough, peripheral edema, headache, abdominal pain, decrease appetite, others)
    • SAE/AE will be collected
    • Blood pressure measurement
    • Blood sampling: (5 ml) with: one Lithium Heparinate tube for letermovir dosage
    • 1 Heparinate Lithium tube (2 ml) for measurements of urea, creatinine, creatinine clearance, liver enzyme (ALAT ASAT GGT PAL), bilirubine
    • Hours of the 3 intakes of pills will be recorded in an individual treatment booklet

  2. At TOP, fetal examination will comprise:

    • Fetal blood sampling (5 ml in a Lithium Heparinate tube for Letermovir dosage) collected at the time of feticide before lethal injection is given in the umbilical vein under ultrasound guidance.
    • Amniotic fluid sampling (5 ml on Lithium heparinate tube for Letermovir dosage) collected by the midwife at the time of artificial rupture of the amniotic membranes.
    • Placental biopsies sampling (2 cotyledons for Letermovir dosage) collected after delivery.
    • SAE/AE will be collected
  3. At day 4 after TOP:

Phone call to collect SAE/AE after TOP

The duration of participation of each woman including data collection will be a maximum of 7 days (3 days before the TOP and 4 days after TOP).

The duration of the study will be 9 months.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
7

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

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

Study Locations

  • France
      • Paris, France, 75015
        • Hôpital Necker - Enfants Malades

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Pregnant woman ≥ 18 years old
  • in her second trimester of pregnancy
  • undergoing TOP for any fetal abnormality
  • no evidence of placental dysfunction.
  • - 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
  • Woman with creatinine clearance <75 ml/mn/1.73m2
  • Woman with liver insufficiency (Child Pugh grade C), AST, ALT 5 x ULN, bilirubin 2 x ULN.
  • Woman with known allergy to Letermovir
  • Contraindication for the administration of Letermovir listed in the SmPC of Prevymis®
  • Woman treated by pimozide, ergot alkaloids, dabigatran, atorvastatin, simvastatin, rosuvastatin, pitavastatine or cyclosporine.
  • Concomitant administration of millepertuis
  • 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: Other
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: letermovir
Maternal administration of 1 tablet of Letermovir (240 mg or 480 mg /day) during 3 days before TOP
Drug: Letermovir

Each patient will receive 1 tablet of Letermovir (240 mg or 480 mg /day) during 3 days before TOP.

5 women will receive 240 mg. 5 women will receive 480 mg.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Time Frame
Concentrations reached in fetal blood relative to EC50 of letermovir.
Time Frame: At termination of pregnancy, on average 3 days after inclusion
At termination of pregnancy, on average 3 days after inclusion

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Assistance Publique - Hôpitaux de Paris

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
URC-CIC Paris Descartes Necker Cochin

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Chair: Marianne LERUEZ-VILLE, PhD & MD, Virology laboratory- reference national Lab for CMV infection -Hôpital Necker-Enfants malades, Paris

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
June 11, 2021

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
November 5, 2021

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
November 12, 2021

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
January 24, 2021

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 29, 2021

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
February 1, 2021

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
March 31, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 26, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • APHP180592
  • 2020-002924-35 (EudraCT Number)

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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