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

Longitudinal Serum and Mucosal RSV Antibodies Following Clesrovimab (Enflonsia™, Merck) Administration in Infants During Their First Respiratory Season or [The EMBRACE Study: Enflonsia™ Monoclonal in Babies - RSV Antibody Concentration Evaluation]

Status
Not yet recruiting
Phases
Phase 4
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT07824167
Enrollment
24
Registered
2026-09-17
Start date
2026-09-01
Completion date
2028-03-01
Last updated
2026-09-17

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

RSV Infection

Keywords

Clesrovimab

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.

Detailed description

The study will enroll 24 infants younger than 8 months who are entering their first RSV season. The study includes minors and may include newborn infants. Written permission will be obtained from a parent or legally authorized representative before any study procedures occur. Infant assent will not be obtained because the participants are too young to provide it. Each infant will receive one injection of clesrovimab as part of the usual care recommended to prevent serious RSV illness. Study staff will collect blood and nasal samples before the injection, at either Day 8 or Day 45, and at Day 181 after injection. Parent or legally authorized representative will also complete one safety follow-up visit by phone call at either Day 8 or Day 45. Each infant will participate for about six months after receiving clesrovimab. Recruitment will invite families of eligible infants through the Emory Children's Center-Vaccine Research Clinic (ECC-VRC), Emory and community outreach, healthcare clinics, electronic health record messages, advertisements, and approved online recruitment methods. Blood, nasal samples, and study data will be stored for the planned study tests. Remaining samples will be stored without information that directly identifies the infant, such as the infant's name or date of birth (de-identified), until the planned tests are complete and the study is closed. They will not be stored for unrelated future research. Study records will be kept as required by Emory, the study sponsor, and applicable rules.

Interventions

BIOLOGICALClesrovimab

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

Sponsors

Emory University
Lead SponsorOTHER
Merck Sharp & Dohme LLC
CollaboratorINDUSTRY

Study design

Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE

Intervention model description

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.

Eligibility

Sex/Gender
ALL
Age
No minimum to 8 Months
Healthy volunteers
No

Inclusion criteria

1. An infant who is \<8 months of age at the time of immunization and born during or entering their first respiratory season. 2. 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. 3. 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. 4. 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. 5. 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. 6. Subject is available to complete the follow-up period, which will be approximately 6 months after receipt of the dose of study drug.

Exclusion criteria

1. Any fever (≥ 100.4°F \[≥ 38.0°C\], regardless of route) or acute illness within 3 days prior to enrollment. 2. 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). 3. Known immunodeficiency, including human immunodeficiency virus (HIV). 4. Any known allergy or hypersensitivity to immunoglobulin products. 5. Hypersensitivity, anaphylaxis, or seizures within 72 hours after any previous administration of a vaccine. 6. Receipt of polyclonal antibodies and/or plasma at any time prior to or planned during the study follow-up period. 7. Receipt of palivizumab, nirsevimab, or other RSV monoclonal antibody or any RSV vaccine at any time prior to or planned during the study. 8. Maternal receipt of an RSV vaccine during her pregnancy with the infant participant. 9. 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. 10. Concurrent enrollment in another interventional study. 11. 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. 12. Unable to obtain baseline blood (minimum 0.5 mL) or nasal sample.

Design outcomes

Primary

MeasureTime frameDescription
Geometric mean concentration (GMC) of serum RSV pre-fusion (preF) binding IgG antibodiesBaseline (Day 1), assigned early follow-up timepoint (Day 8 or Day 45) and Day 181RSV 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.
Geometric mean concentration (GMC) of nasal RSV pre-fusion (preF) binding IgG antibodiesBaseline (Day 1), assigned early follow-up timepoint (Day 8 or Day 45) and Day 181RSV 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.
Geometric mean titers (GMT) of serum RSV-A neutralizing antibodiesBaseline (Day 1), assigned early follow-up timepoint (Day 8 or Day 45) and Day 181Serum 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).

Secondary

MeasureTime frameDescription
Serum Geometric mean concentration (GMC) of clesrovimabBaseline (Day 1), assigned early follow-up timepoint (Day 8 or Day 45) and Day 181Serum clesrovimab concentrations will be reported in concentration units and summarized as geometric mean concentrations (GMC) at each study timepoint.
Urea-normalized GMC of clesrovimab in the nasal mucosaBaseline (Day 1), assigned early follow-up timepoint (Day 8 or Day 45) and Day 181Clesrovimab concentrations will be normalized to urea concentration for nasal samples to account for variability in epithelial lining fluid dilution. Urea-normalized nasal clesrovimab concentrations will be summarized as GMC.

Countries

United States

Contacts

CONTACTJessica McCaffery, PhD
ecc.vaccine@emory.edu404-727-4044
CONTACTChristina Rostad, MD
PRINCIPAL_INVESTIGATORChristina Rostad, MD

Emory University

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Sep 18, 2026