Evaluating an mRNA vaccine for preventing cytomegalovirus infection in transplant patients

A Phase 2, Observer-Blind, Placebo-Controlled Proof-of-Concept Trial to Evaluate Efficacy, Safety, and Immunogenicity of mRNA-1647 Cytomegalovirus Vaccine in Patients Who Have Undergone Allogeneic Hematopoietic Cell Transplantation (HCT)

Phase 2 Interventional ModernaTX, Inc. · NCT05683457

This study is testing if an mRNA vaccine can help prevent cytomegalovirus infection in transplant patients who are at high risk.

Quick facts

PhasePhase 2
Study typeInterventional
Enrollment224 (estimated)
Ages18 Years and up
SexAll
SponsorModernaTX, Inc. Industry-sponsored
Drugs / interventionsalemtuzumab, cyclophosphamide
Locations3 sites (Boston, Massachusetts and 2 other locations)
Trial IDNCT05683457 on ClinicalTrials.gov

What this trial studies

This study aims to assess the efficacy and safety of the mRNA-1647 vaccine compared to a placebo in preventing clinically significant cytomegalovirus infection in patients who have undergone allogeneic hematopoietic cell transplantation. Participants will be monitored from Day 100 post-transplant through Month 9 post-transplant to evaluate the vaccine's effectiveness after the cessation of CMV prophylactic treatment. The study focuses on high-risk individuals who are CMV-seropositive, ensuring a targeted approach to this vulnerable population.

Who should consider this trial

Good fit: Ideal candidates for this study are CMV-seropositive individuals who have received an allogeneic hematopoietic cell transplantation and are at high risk for CMV infection.

Not a fit: Patients who are CMV-seronegative or those who have not undergone allogeneic hematopoietic cell transplantation may not benefit from this study.

Why it matters

Potential benefit: If successful, this vaccine could significantly reduce the incidence of cytomegalovirus infections in high-risk transplant patients, improving their overall health outcomes.

How similar studies have performed: While there have been studies on CMV vaccines, this specific mRNA approach is relatively novel and has not been extensively tested in this context.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Receipt of an allogeneic HCT.
* CMV-seropositive, defined as a documented positive test for anti-CMV IgG.
* High-risk for CMV: HCT from related, unrelated, or haploidentical donor with post-transplant cyclophosphamide for graft-versus-host-disease (GVHD) prophylaxis; or HCT from related or unrelated donor with at least one mismatch at any of the following human leukocyte antigen (HLA) gene loci (HLA-A, B, C, and DRB1); or HCT from related or unrelated donor with myeloablative conditioning.
* Persons of nonchildbearing potential or of childbearing potential with negative urine or serum pregnancy test on the day of first study injection.
* Persons of childbearing potential who have practiced adequate contraception or have abstained from all activities that could result in pregnancy for at least 28 days prior to the first dose.
* Persons of childbearing potential who have agreed to continue adequate contraception or abstain from all activities that could result in pregnancy through 3 months after last study injection.
* Persons who are not currently breast/chestfeeding.
* Willingness to comply with study procedures and provide written informed consent.

Exclusion Criteria:

* History of a diagnosis or condition that, in the judgment of the Investigator, may affect participant safety, assessment of safety endpoints, assessment of immune response, or adherence to study procedures.
* A documented positive human immunodeficiency virus (HIV) test.
* Treatment with alemtuzumab (Campath®), antithymocyte globulin (ATG), or any equivalent in-vivo T cell depleting agent within 12 months.
* HCT with ex-vivo T cell depletion.
* Low risk for CMV: HCT from related or unrelated donor with reduced intensity conditioning (RIC) and no other high-risk features.
* History of prior hematopoietic cell transplantation within 12 months.
* Receipt of prior investigational CMV vaccines or participation in another CMV therapeutic study that may interfere with study outcome measures as determined by the Investigator.
* Suspected or known allergic reaction to any component of any mRNA vaccine or its excipients.

Where this trial is running

Boston, Massachusetts and 2 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Cytomegalovirus InfectionHuman cytomegalovirusHuman HerpesvirusmRNA-1647ModernaCMVCytomegalovirus VaccineCytomegalovirus Infections
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.