A Study to Investigate The Safety, Tolerability, And Immune Response of a Range of Doses of mRNA-1769 Compared With Placebo in Healthy Participants From ≥18 Years of Age to <50 Years of Age

July 15, 2025 updated by: ModernaTX, Inc.

A Randomised, Placebo-Controlled, Dose-Ranging, Observer-Blind Phase 1/2 Study to Evaluate the Safety, Tolerability, and Immunogenicity of mRNA-1769 in Healthy Participants

The goal of this study is to assess the safety, tolerability and immunogenicity of mRNA-1769 in healthy adult participants.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

351

Phase

  • Phase 2
  • Phase 1

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

  • United Kingdom
      • Bradford, United Kingdom, BD9 6RJ
        • Bradford Teaching Hospitals NHS Foundation Trust
      • Bristol, United Kingdom, BS2 8DX
        • University Hospitals Bristol and Weston NHS Foundation Trust
      • Corby, United Kingdom, NN17 2UR
        • Lakeside Healthcare Research
      • Leicester, United Kingdom, LE1 5WW
        • University Hospitals of Leicester
      • Liverpool, United Kingdom, L7 8XP
        • Liverpool University Hospitals NHS Foundation Trust
      • London, United Kingdom, NW3 2QG
        • Royal Free London NHS Foundation Trust
      • London, United Kingdom, NW1 2PG
        • University College London Hospitals
      • London, United Kingdom, SW10 9NH
        • Chelsea and Westminster Hospital NHS Foundation Trust
      • London, United Kingdom, E1 4DG
        • Barts Health NHS Trust
      • Manchester, United Kingdom, M23 9QZ
        • Medicines Evaluation Unit
      • Oxford, United Kingdom, OX3 7LE
        • Centre for Clinical Vaccinology and Tropical Medicine (CCVTM)
      • Wrexham, United Kingdom, LL13 7YP
        • North Wales Clinical Research Facility Centre

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

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Has a body mass index (BMI) between ≥18 kilogram per square meter (kg/m^2) to ≤39 kg/m^2.
  • For female participants of childbearing potential: must have a negative highly sensitive pregnancy test with 28 days before the first dose of study drug, uses approved contraception during the study intervention period and for at least 3 months after the last dose of study drug, and not currently breastfeeding.

Exclusion Criteria:

  • History of smallpox vaccination, vaccination with any poxvirus-based vaccine, history of of/or recent exposure to Mpox (MPX) (defined as close contact with a confirmed case of MPX within the past 14 days).
  • Participant should not have any significant, progressive, unstable, or uncontrolled clinical condition, including any condition that may affect participant safety, assessment of safety endpoints, assessment of immune response, or adherence to study procedures per Investigator judgement.
  • Participant is undergoing investigations for a potential chronic medical disorder.
  • Bleeding disorder considered a contraindication to IM injection or phlebotomy.
  • Dermatologic conditions that could affect local solicited AR assessments.
  • History of anaphylactic reaction or allergic reactions that required medical intervention following any vaccine.
  • Known or suspected allergy to any component of mRNA-1769.
  • History of malignancy within previous 10 years (excluding non-melanoma skin cancer).
  • Participant has any medical, psychiatric, or occupational condition, including reported history of drug or alcohol abuse, that, in the opinion of the Investigator, might pose additional risk due to participation in the study or could interfere with the interpretation of study results.
  • Participant has received systemic immunosuppressants or immune-modifying drugs for >14 days in total within 6 months prior to Screening (for corticosteroids, ≥10 mg/day of prednisone or equivalent) or is anticipating the need for immunosuppressive treatment at any time during participation in the study. Topical tacrolimus is allowed if not used within 14 days prior to the day of enrolment. Participants may be rescheduled for enrolment if they no longer meet this criterion within the Screening Period. Inhaled, nasal, and topical steroids are allowed.
  • Receipt or planned receipt of: Any vaccine(s), authorised or approved by local health agency, including mRNA vaccine, ≤28 days prior to the first injection through 28 days after the last dose of investigational (IMP).
  • Intravenous blood products (red cells, platelets, immunoglobulins) within 3 months prior to the first injection up to the end of the study.
  • Participated in an interventional study/received an investigational product within 28 days prior to the Screening Period or plans to do so while enroled in this study.

Note: Other inclusion and exclusion criteria may apply.

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: Sequential Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: mRNA-1769 Dose A
Participants will receive intramuscular (IM) injection of mRNA-1769 at Dose A on Day 1 and Day 29.
Biological: mRNA-1769
Sterile liquid for injection
Experimental: mRNA-1769 Dose B
Participants will receive IM injection of mRNA-1769 at Dose B on Day 1 and Day 29.
Biological: mRNA-1769
Sterile liquid for injection
Experimental: mRNA-1769 Dose C
Participants will receive IM injection of mRNA-1769 at Dose C on Day 1 and Day 29.
Biological: mRNA-1769
Sterile liquid for injection
Placebo Comparator: Placebo
Participants will receive IM injection of placebo matched to mRNA-1769 on Day 1 and Day 29.
Other: Placebo
0.9% sodium chloride injection (normal saline)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Number of Solicited Local and Systemic Reactogenicity Adverse Reactions (ARs) Through 7 Days After Each Investigational Medicinal Product (IMP)
Time Frame: Up to Day 35
Up to Day 35
Number of Unsolicited Adverse Events (AEs) Through 7 Days After Each IMP
Time Frame: Up to Day 57
Up to Day 57
Number of Participants with Medically-Attended AEs (MAAEs)
Time Frame: Day 1 up to Day 395
Day 1 up to Day 395
Number of Participants with Adverse Events of Special Interest (AESIs)
Time Frame: Day 1 up to Day 395
Day 1 up to Day 395
Number of Participants with Serious Adverse Events (SAEs)
Time Frame: Day 1 up to Day 395
Day 1 up to Day 395
Number of Participants with AEs Leading to Study and/or Treatment Discontinuation
Time Frame: Day 1 up to Day 395
Day 1 up to Day 395

Secondary Outcome Measures

Outcome Measure
Time Frame
Geometric Mean Titer (GMT) of Neutralising Antibody (nAb) against Mpox Virus (MPXV) by Plaque reduction neutralisation test (PRNT)
Time Frame: Days 1 and 43
Days 1 and 43
Percentage of Participants With Seroconversion Based on Neutralising Antibody Responses Against MPXV
Time Frame: Days 1 and 43
Days 1 and 43
Geometric Mean Concentration of Binding Antibodies (bAbs) Against MPXV Antigens by Meso Scale Discovery (MSD) Assay
Time Frame: Days 1, 29, 43, and 57
Days 1, 29, 43, and 57
Percentage of Participants With Seroconversion Based on Binding Antibodies (bAb) Responses against MPXV
Time Frame: Days 1, 29, 43, and 57
Days 1, 29, 43, and 57
Geometric Mean Titer of Neutralising Antibody Against Vaccinia Virus (VACV) by Plaque Reduction Neutralisation Test (PRNT)
Time Frame: Days 1 and 43
Days 1 and 43
Percentage of Participants With Seroconversion Based on Neutralising Antibody Responses Against Vaccinia Virus
Time Frame: Days 1 and 43
Days 1 and 43
Geometric Mean Concentration of Binding Antibodies Against Vaccinia Virus Antigens by Meso Scale Discovery Assay
Time Frame: Days 1, 29, 43, and 57
Days 1, 29, 43, and 57
Percentage of Participants With Seroconversion Based on Binding Antibodies Responses Against Vaccinia Virus
Time Frame: Days 1, 29, 43, and 57
Days 1, 29, 43, and 57

Collaborators and Investigators

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

Sponsor

ModernaTX, Inc.

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)

August 15, 2023

Primary Completion (Actual)

July 8, 2025

Study Completion (Actual)

July 8, 2025

Study Registration Dates

First Submitted

August 9, 2023

First Submitted That Met QC Criteria

August 9, 2023

First Posted (Actual)

August 16, 2023

Study Record Updates

Last Update Posted (Actual)

July 16, 2025

Last Update Submitted That Met QC Criteria

July 15, 2025

Last Verified

July 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • mRNA-1769-P101

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

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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