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NCT Number: NCT05683457

A Study to Evaluate the Efficacy, Safety, and Immunogenicity of mRNA-1647 Cytomegalovirus (CMV) Vaccine in Allogenic Hematopoietic Cell Transplantation (HCT) Participants.

The main purpose of the study is to evaluate the efficacy and safety of mRNA-1647 compared to placebo to prevent first clinically significant cytomegalovirus infection (CS-CMVi) in the period following cessation of CMV prophylactic treatment (for example, letermovir) on Day 100 post-HCT through Month 9 post-HCT.

Active, Not Recruiting

This study is active but is not currently recruiting participants.

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Key information

Conditions

Cytomegalovirus Infection Cytomegalovirus Infections DNA Virus Infections Herpes Simplex Herpesviridae Infections Infections Skin Diseases Skin Diseases, Infectious Skin Diseases, Viral Skin and Connective Tissue Diseases Virus Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

Primary location

Dana-Farber Cancer Institute, Boston, Massachusetts, United States

Loading trial locations.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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.

Treatment and study plan

mRNA-1647

Biological

Lyophilized product that is reconstituted with 0.9% sodium chloride (normal saline).

Placebo

Biological

0.9% sodium chloride (normal saline) injection

Primary outcomes

  1. Time to the First Occurrence of an CS-CMVi Event as Measured by initiation of anti-CMV Antiviral Therapy

    Time frame: Day 100 to Month 9

  2. Number of Participants with Solicited Local and Systemic Reactogenicity Adverse Reactions (ARs)

    Time frame: Up to Day 187 (7 days after last study injection)

  3. Number of Unsolicited Adverse Events (AEs)

    Time frame: Up to Day 205 (25 days after last study injection)

  4. Number of Participants with Severe AEs

    Time frame: Up to Day 365

  5. Number of Participants with Serious Adverse Events (SAEs)

    Time frame: Up to Day 365

  6. Number of Participants with Grade ≥3 Acute Graft-Versus-Host Disease (GVHD)

    Time frame: Up to Day 365

Secondary outcomes

  1. Number of Participants with First Occurrence of All CS-CMVi Events as Measured by Initiation of Anti-CMV Antiviral and/or End-Organ Disease

    Time frame: Day 100 to Month 9

  2. Number of Participants with an Occurrence of CMV Viremia

    Time frame: Day 100 to Month 9

    CMV Viremia is defined as ≥300 international units/milliliters (IU/mL).

  3. Number of Participants with CMV End-Organ Disease

    Time frame: Day 100 to Month 9

  4. Duration of CMV Viremia

    Time frame: Day 100 to Month 9

  5. Duration of CMV Treatment

    Time frame: Day 100 to Month 9

  6. Number of Participants with Non-Relapse Mortality at 9 Months Post-HCT.

    Time frame: Month 9

  7. Titer of CMV-Specific Neutralizing Antibody (nAb)

    Time frame: Days 42, 67, 92, 117, 180, 205 and 270

  8. Geometric Mean Titer (GMT) of Anti-gB-Specific Immunoglobulin G (IgG) and Anti-Pentamer-Specific IgG as Measured by Enzyme-Linked Immunosorbent Assay (ELISA)

    Time frame: Days 42, 67, 92, 117, 180, 205 and 270

  9. Geometric Mean Concentration (GMC) of Anti-gB-Specific Immunoglobulin G (IgG) and Anti-Pentamer-Specific IgG as Measured by Enzyme-Linked Immunosorbent Assay (ELISA)

    Time frame: Days 42, 67, 92, 117, 180, 205 and 270

  10. Geometric Mean Fold Rise (GMFR) of Postbaseline/Baseline GMTs or GMCs

    Time frame: Days 42, 67, 92, 117, 180, 205 and 270

Sponsors and collaborators

Lead sponsor

ModernaTX, Inc.

Industry

Registry information

Official study title

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)

Important dates

Study start
2023
Primary completion
2026
Study completion
2026
First posted
Jan 13, 2023
Registry last updated
May 18, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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