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

NCT05995275 | Completed Phase 1

• 1 other identifier: mRNA-1769-P101
• Study Type: interventional
• Target: 351
• Locations: 1 country
• Sites: 12

Brief Summary

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

Conditions

Smallpox; Mpox

Keywords

mRNA-1769 vaccine; mRNA-1769; Moderna

Outcome Measures

Primary Outcomes (6)

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

  Up to Day 35

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

  Up to Day 57

• Number of Participants with Medically-Attended AEs (MAAEs)

  Day 1 up to Day 395

• Number of Participants with Adverse Events of Special Interest (AESIs)

  Day 1 up to Day 395

• Number of Participants with Serious Adverse Events (SAEs)

  Day 1 up to Day 395

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

  Day 1 up to Day 395

Secondary Outcomes (8)

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

  Days 1 and 43

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

  Days 1 and 43

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

  Days 1, 29, 43, and 57

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

  Days 1, 29, 43, and 57

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

  Days 1 and 43

Study Arms (4)

mRNA-1769 Dose A

EXPERIMENTAL

Participants will receive intramuscular (IM) injection of mRNA-1769 at Dose A on Day 1 and Day 29.

Biological: mRNA-1769

mRNA-1769 Dose B

EXPERIMENTAL

Participants will receive IM injection of mRNA-1769 at Dose B on Day 1 and Day 29.

Biological: mRNA-1769

mRNA-1769 Dose C

EXPERIMENTAL

Participants will receive IM injection of mRNA-1769 at Dose C on Day 1 and Day 29.

Biological: mRNA-1769

Placebo

PLACEBO COMPARATOR

Participants will receive IM injection of placebo matched to mRNA-1769 on Day 1 and Day 29.

Other: Placebo

Interventions

mRNA-1769 BIOLOGICAL

Sterile liquid for injection

mRNA-1769 Dose A; mRNA-1769 Dose B; mRNA-1769 Dose C

Placebo OTHER

0.9% sodium chloride injection (normal saline)

Placebo

Eligibility Criteria

• Age: 18 Years - 49 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• 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.

You may not qualify if:

• 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.

Sponsors & Collaborators

• ModernaTX, Inc.: lead

Study Sites (12)

Bradford Teaching Hospitals NHS Foundation Trust

Bradford, BD9 6RJ, United Kingdom

Location

University Hospitals Bristol and Weston NHS Foundation Trust

Bristol, BS2 8DX, United Kingdom

Location

Lakeside Healthcare Research

Corby, NN17 2UR, United Kingdom

Location

University Hospitals of Leicester

Leicester, LE1 5WW, United Kingdom

Location

Liverpool University Hospitals NHS Foundation Trust

Liverpool, L7 8XP, United Kingdom

Location

Barts Health NHS Trust

London, E1 4DG, United Kingdom

Location

University College London Hospitals

London, NW1 2PG, United Kingdom

Location

Royal Free London NHS Foundation Trust

London, NW3 2QG, United Kingdom

Location

Chelsea and Westminster Hospital NHS Foundation Trust

London, SW10 9NH, United Kingdom

Location

Medicines Evaluation Unit

Manchester, M23 9QZ, United Kingdom

Location

Centre for Clinical Vaccinology and Tropical Medicine (CCVTM)

Oxford, OX3 7LE, United Kingdom

Location

North Wales Clinical Research Facility Centre

Wrexham, LL13 7YP, United Kingdom

Location

MeSH Terms

Conditions

Smallpox; Mpox, Monkeypox

Condition Hierarchy (Ancestors)

Poxviridae Infections; DNA Virus Infections; Virus Diseases; Infections; Primate Diseases; Animal Diseases; Rodent Diseases

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: PREVENTION
• Intervention Model: SEQUENTIAL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: August 9, 2023
• First Posted: August 16, 2023
• Study Start: August 15, 2023
• Primary Completion: July 8, 2025
• Study Completion: July 8, 2025
• Last Updated: July 16, 2025

Record last verified: 2025-07

Locations

GB (12)