The EMBRACE Study: Enflonsia Monoclonal in Babies - RSV Antibody Concentration Evaluation

NCT07824167 | Not Yet Recruiting Phase 4 DMC FDA Drug

• 1 other identifier: 2026P001574
• Study Type: interventional
• Target: 24
• Locations: 1 country
• Sites: 1

Brief Summary

Clesrovimab is an FDA-approved antibody drug recommended for infants younger than 8 months who are entering their first respiratory syncytial virus (RSV) season and whose mothers did not receive an RSV vaccine during pregnancy. It is given to help prevent severe RSV illness. This study will measure clesrovimab and other RSV antibodies in infants' blood and noses to learn how much of the drug reaches the nose, how long the antibodies remain, and how antibody levels change if an infant becomes infected with RSV.

Conditions

RSV Infection

Keywords

Clesrovimab

Outcome Measures

Primary Outcomes (3)

• Geometric mean concentration (GMC) of serum RSV pre-fusion (preF) binding IgG antibodies

  RSV pre-fusion (preF) IgG binding antibodies in serum specimens will be quantified. Assay results will be reported as concentrations (arbitrary units per milliliter, AU/mL) derived from a calibrated standard curve. Serum RSV preF IgG concentrations will be summarized as geometric mean concentrations (GMC) at each study timepoint.

  Baseline (Day 1), assigned early follow-up timepoint (Day 8 or Day 45) and Day 181

• Geometric mean concentration (GMC) of nasal RSV pre-fusion (preF) binding IgG antibodies

  RSV pre-fusion (preF) IgG binding antibodies in nasal specimens will be quantified. Assay results will be reported as concentrations (arbitrary units per milliliter, AU/mL) derived from a calibrated standard curve. For nasal specimens, RSV preF IgG concentrations will be normalized to total human IgG concentration. Normalized nasal antibody values will be summarized as GMC.

  Baseline (Day 1), assigned early follow-up timepoint (Day 8 or Day 45) and Day 181

• Geometric mean titers (GMT) of serum RSV-A neutralizing antibodies

  Serum RSV neutralizing antibody titers will be measured using a microneutralization assay. Neutralizing antibody titers will be reported as reciprocal dilution EC50 titers (the serum dilution resulting in 50% neutralization) and summarized as geometric mean titers (GMTs).

  Baseline (Day 1), assigned early follow-up timepoint (Day 8 or Day 45) and Day 181

Secondary Outcomes (2)

• Serum Geometric mean concentration (GMC) of clesrovimab

  Baseline (Day 1), assigned early follow-up timepoint (Day 8 or Day 45) and Day 181

• Urea-normalized GMC of clesrovimab in the nasal mucosa

  Baseline (Day 1), assigned early follow-up timepoint (Day 8 or Day 45) and Day 181

Study Arms (1)

Infants Receiving Clesrovimab (Enflonsia™)

EXPERIMENTAL

Participants will receive a single injection of clesrovimab intramuscularly in the anterolateral thigh at a dose of 105 mg, at Visit 1 (Day 1).

Biological: Clesrovimab

Interventions

Clesrovimab BIOLOGICAL

Clesrovimab (ENFLONSIA™) is a commercially available product that is administered as part of standard-of-care RSV prevention.

Also known as: Enflonsia™

Infants Receiving Clesrovimab (Enflonsia™)

Eligibility Criteria

• Age: Up to 8 Months
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17)

You may qualify if:

• An infant who is \<8 months of age at the time of immunization and born during or entering their first respiratory season.
• The infant is in good health as established by medical history and investigator's discretion before entering the study. Chronic medical conditions are acceptable, provided that they are stable.
• Written informed consent is obtained from the participant's parent(s)/legally authorized representative(s) (LAR) prior to performing any study specific procedures, including screening evaluations.
• At least one parent/legally authorized representative of the subject is willing and able to maintain communication with the study site for the duration of the study.
• Subject's parent(s)/legally authorized representative(s) is able to understand and comply with the requirements of the protocol including follow-up and illness visits as judged by the investigator.
• Subject is available to complete the follow-up period, which will be approximately 6 months after receipt of the dose of study drug.

You may not qualify if:

• Any fever (≥ 100.4°F \[≥ 38.0°C\], regardless of route) or acute illness within 3 days prior to enrollment.
• Any current or expected receipt of immunosuppressive agents including systemic steroids (except for the use of topical steroids according to the judgment of the investigator).
• Known immunodeficiency, including human immunodeficiency virus (HIV).
• Any known allergy or hypersensitivity to immunoglobulin products.
• Hypersensitivity, anaphylaxis, or seizures within 72 hours after any previous administration of a vaccine.
• Receipt of polyclonal antibodies and/or plasma at any time prior to or planned during the study follow-up period.
• Receipt of palivizumab, nirsevimab, or other RSV monoclonal antibody or any RSV vaccine at any time prior to or planned during the study.
• Maternal receipt of an RSV vaccine during her pregnancy with the infant participant.
• Use of any investigational product or non-registered product (drug or vaccine) other than the study product during the period starting 30 days before study product administration, or planned use during the study period.
• Concurrent enrollment in another interventional study.
• Any other condition that, in the judgment of the investigator, would be a risk to subject's safety and/or may interfere with study procedures or interpretation of results.
• Unable to obtain baseline blood (minimum 0.5 mL) or nasal sample.

Sponsors & Collaborators

• Emory University: lead
• Merck Sharp & Dohme LLC: collaborator

Study Sites (1)

Emory Children's Center-Vaccine Research Clinic

Atlanta, Georgia, 30322, United States

Location

MeSH Terms

Conditions

Respiratory Syncytial Virus Infections

Condition Hierarchy (Ancestors)

Pneumovirus Infections; Paramyxoviridae Infections; Mononegavirales Infections; RNA Virus Infections; Virus Diseases; Infections

Study Officials

• Christina Rostad, MD

  Emory University

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Jessica McCaffery, PhD

CONTACT

404-727-4044; ecc.vaccine@emory.edu

Christina Rostad, MD

CONTACT

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: NA
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Associate Professor

Model Details: This is a Phase 4, open-label, single-center, interventional clinical study designed to characterize immunologic and pharmacokinetic responses following administration of clesrovimab. The study follows a non-randomized design. No control group or comparator treatment is included.

Study Record Dates

• First Submitted: September 11, 2026
• First Posted: September 17, 2026
• Study Start: September 1, 2026
• Primary Completion (Estimated): March 1, 2028
• Study Completion (Estimated): March 1, 2028
• Last Updated: September 17, 2026

Record last verified: 2026-09

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)