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SmallpoxPhase 1/2NCT05995275

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

A Phase 1/2 study testing mRNA-1769 in people with Smallpox and Mpox, run by ModernaTX, Inc. at 12 sites in United Kingdom.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

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

Who is it for?
Ages 18 to 49 yearsHealthy volunteers can take part
Conditions the study is for
Smallpox, Mpox
What is being tested?
mRNA-1769
Type of treatment
Injection or infusion
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
351 participants
Where
12 sitesUnited Kingdom
Study dates
15 Aug 2023to 8 Jul 2025
Phase
Phase 1/2
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 to 49 years
  • All sexes
  • Healthy volunteers accepted
  • Adult

Who may be able to join

  • 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.

Who cannot join

  • 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.
Show all 14Show fewer
  • 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.

Trial locations and contacts

12 sites in 1 country.

12 sites in 1 country

United Kingdom12 sites

  • Bradford Teaching Hospitals NHS Foundation Trust

    Bradford, BD9 6RJ

  • University Hospitals Bristol and Weston NHS Foundation Trust

    Bristol, BS2 8DX

  • Lakeside Healthcare Research

    Corby, NN17 2UR

  • University Hospitals of Leicester

    Leicester, LE1 5WW

  • Liverpool University Hospitals NHS Foundation Trust

    Liverpool, L7 8XP

  • Barts Health NHS Trust

    London, E1 4DG

  • University College London Hospitals

    London, NW1 2PG

  • Royal Free London NHS Foundation Trust

    London, NW3 2QG

  • Chelsea and Westminster Hospital NHS Foundation Trust

    London, SW10 9NH

  • Medicines Evaluation Unit

    Manchester, M23 9QZ

  • Centre for Clinical Vaccinology and Tropical Medicine (CCVTM)

    Oxford, OX3 7LE

  • North Wales Clinical Research Facility Centre

    Wrexham, LL13 7YP

Other trials in United Kingdom

About this study

Official title: 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.

Conditions
Smallpox, Mpox
Being tested
mRNA-1769, Placebo
Keywords
mRNA-1769 vaccine, mRNA-1769, Moderna
Medical subject headings
Smallpox, Mpox, Monkeypox

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • mRNA-1769Biological

    Sterile liquid for injection

  • PlaceboOther

    0.9% sodium chloride injection (normal saline)

Study groups in NCT05995275
Study groupRoleWhat they receive
mRNA-1769 Dose AExperimentalParticipants will receive intramuscular (IM) injection of mRNA-1769 at Dose A on Day 1 and Day 29.
Receives: Biological: mRNA-1769
mRNA-1769 Dose BExperimentalParticipants will receive IM injection of mRNA-1769 at Dose B on Day 1 and Day 29.
Receives: Biological: mRNA-1769
mRNA-1769 Dose CExperimentalParticipants will receive IM injection of mRNA-1769 at Dose C on Day 1 and Day 29.
Receives: Biological: mRNA-1769
PlaceboPlacebo comparatorParticipants will receive IM injection of placebo matched to mRNA-1769 on Day 1 and Day 29.
Receives: Other: Placebo

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Number of Solicited Local and Systemic Reactogenicity Adverse Reactions (ARs) Through 7 Days After Each Investigational Medicinal Product (IMP)

    Measured: Up to Day 35

  2. Number of Unsolicited Adverse Events (AEs) Through 7 Days After Each IMP

    Measured: Up to Day 57

  3. Number of Participants with Medically-Attended AEs (MAAEs)

    Measured: Day 1 up to Day 395

  4. Number of Participants with Adverse Events of Special Interest (AESIs)

    Measured: Day 1 up to Day 395

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

    Measured: Day 1 up to Day 395

  6. Number of Participants with AEs Leading to Study and/or Treatment Discontinuation

    Measured: Day 1 up to Day 395

Secondary outcomes (8)

  1. Geometric Mean Titer (GMT) of Neutralising Antibody (nAb) against Mpox Virus (MPXV) by Plaque reduction neutralisation test (PRNT)

    Measured: Days 1 and 43

  2. Percentage of Participants With Seroconversion Based on Neutralising Antibody Responses Against MPXV

    Measured: Days 1 and 43

  3. Geometric Mean Concentration of Binding Antibodies (bAbs) Against MPXV Antigens by Meso Scale Discovery (MSD) Assay

    Measured: Days 1, 29, 43, and 57

  4. Percentage of Participants With Seroconversion Based on Binding Antibodies (bAb) Responses against MPXV

    Measured: Days 1, 29, 43, and 57

  5. Geometric Mean Titer of Neutralising Antibody Against Vaccinia Virus (VACV) by Plaque Reduction Neutralisation Test (PRNT)

    Measured: Days 1 and 43

  6. Percentage of Participants With Seroconversion Based on Neutralising Antibody Responses Against Vaccinia Virus

    Measured: Days 1 and 43

  7. Geometric Mean Concentration of Binding Antibodies Against Vaccinia Virus Antigens by Meso Scale Discovery Assay

    Measured: Days 1, 29, 43, and 57

  8. Percentage of Participants With Seroconversion Based on Binding Antibodies Responses Against Vaccinia Virus

    Measured: Days 1, 29, 43, and 57

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted16 Aug 2023
  2. Study start15 Aug 2023
  3. Primary completion8 Jul 2025
  4. Study completion8 Jul 2025

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 1/2
Primary purpose
Prevention
Allocation
Randomised
Intervention model
Sequential
Masking
Quadruple blind
Who is masked
Participant, Care provider, Investigator, Outcomes assessor
Enrolment
351 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT05995275
Sponsor's protocol ID
mRNA-1769-P101
Status last verified
Jul 2025
First submitted
9 Aug 2023
Last updated
16 Jul 2025
Results posted
No
FDA-regulated drug
No
FDA-regulated device
No

Questions about this trial

What is this clinical trial studying?

A Phase 1/2 study testing mRNA-1769 in people with Smallpox and Mpox, run by ModernaTX, Inc. at 12 sites in United Kingdom.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 2 inclusion and 14 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 16 Jul 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 12 sites in United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this combined phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

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). The study lists 6 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT05995275.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 16 Jul 2025.

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