Phase 3
N=1,003
Clesrovimab (MK-1654) in Infants and Children at Increased Risk for Severe Respiratory Syncytial Virus (RSV) Disease (MK-1654-007)
RSV Infection
Bottom Line
View on ClinicalTrials.gov: NCT04938830 ↗Enrolled (actual)
1,003
Serious AEs
24.4%
Results posted
May 2026
Primary outcome: Primary: Number of Participants With Solicited Injection-site Adverse Events (AEs) in RSV Season 1 — 31; 32; 39; 54 Participants
Study Design & Population
- Study type
- Interventional
- Phase
- Phase 3
- Interventions
- Clesrovimab (Biological); Palivizumab (Biological); Placebo (Biological)
- Age
- Pediatric
- Sex
- All
- Sponsor
- Merck Sharp & Dohme LLC
- Primary completion
- Apr 2025
Outcome Measures
| Outcome | Result | p-value |
|---|---|---|
| PRIMARY Number of Participants With Solicited Injection-site Adverse Events (AEs) in RSV Season 1 |
31; 32; 39; 54; 31; 28 | — |
| PRIMARY Number of Participants With Solicited Daily Body Temperatures With Fever in RSV Season 1 |
4; 6 | — |
| PRIMARY Number of Participants With Solicited Systemic AEs in RSV Season 1 |
67; 66; 143; 168; 94; 110 | — |
| PRIMARY Number of Participants With Anaphylaxis/Hypersensitivity AEs of Special Interest (AESI) in RSV Season 1 |
0; 0 | — |
| PRIMARY Number of Participants With Rash AESI in RSV Season 1 |
2; 0; 1; 1 | — |
| PRIMARY Number of Participants With Nonserious AEs in RSV Season 1 |
353; 379 | — |
| PRIMARY Number of Participants With Serious AEs (SAEs) Through the Duration of Participation in RSV Season 1 |
122; 137 | — |
| SECONDARY Number of Cases of RSV-associated Medically Attended Lower Respiratory Infection (MALRI) in RSV Season 1 |
15; 16 | — |
| SECONDARY Number of Cases of RSV-associated Hospitalization in RSV Season 1 |
5; 8 | — |
| SECONDARY Number of Participants With Solicited Injection-site AEs in RSV Season 2 |
3; 2; 7; 5; 4; 1 | — |
| SECONDARY Number of Participants With Solicited Daily Body Temperature With Fever in RSV Season 2 |
0; 3 | — |
| SECONDARY Number of Participants With Solicited Systemic AEs in RSV Season 2 |
12; 7; 12; 24; 15; 9 | — |
| SECONDARY Number of Participants With Anaphylaxis/Hypersensitivity AESI in RSV Season 2 |
0; 0 | — |
| SECONDARY Number of Participants With Rash AESI in RSV Season 2 |
0; 0; 0; 3 | — |
| SECONDARY Number of Participants With Nonserious AEs in RSV Season 2 |
85; 87 | — |
| SECONDARY Number of Participants With SAEs in RSV Season 2 |
25; 26 | — |
| SECONDARY Concentration of Clesrovimab in RSV Season 1 |
148.7; 11.8; 2.9 | — |
| SECONDARY Concentration of Clesrovimab in RSV Season 2 |
170.0; 14.4 | — |
Summary
This study aims to evaluate the safety and tolerability of clesrovimab compared to palivizumab as assessed by the proportion of participants experiencing adverse events (AEs).
Eligibility Criteria
Inclusion Criteria
- Participants at increased risk for severe RSV infection recommended to receive palivizumab in accordance with national or local guidelines or professional society recommendations and meet defined criteria for the Early or Moderate Pre-term Group or the chronic lung disease (CLD)/congenital heart disease (CHD) Group.
- Is available to complete the follow-up period.
Additional inclusion criteria for participation in RSV Season 2:
- RSV Season 2 participants enrolled in the CLD/CHD Group in RSV Season 1. Participants with CHD must also have the following:
- Hemodynamically significant CHD at the beginning of RSV Season 2, or
- If the participant has had surgically repaired hemodynamically significant CHD that did not include extracorporeal membrane oxygenation (ECMO) or cardiopulmonary bypass: 1) continues to require medications to manage CHD, or 2) any additional medical intervention related to their CHD.
- RSV Season 2 participants enrolled in the Early or Moderate Pre-term Group in RSV Season 1, with the following:
- Neuromuscular disease or congenital pulmonary anomaly that impairs the ability to clear secretions from the upper airway because of ineffective cough
- Down Syndrome (trisomy of chromosome 21)
- Cystic fibrosis with nutritional compromise
- Native Americans and Alaskan Indians or other indigenous populations at high risk for severe RSV disease
Exclusion Criteria
- Requires mechanical ventilation at time of enrollment.
- Has a life expectancy <6 months.
- Has known hepatic or renal dysfunction, or chronic seizure disorder.
- Is hospitalized at the time of randomization unless discharge is expected within 7 days after randomization.
- Has severe immunodeficiency or is severely immunocompromised.
- Has known hypersensitivity to any component of clesrovimab or palivizumab.
Additional exclusion criteria for participation in RSV Season 2:
- Had 1) ECMO or 2) surgical intervention during the RSV season for CHD and required cardiopulmonary bypass during the procedure in RSV Season 1.
Data sourced from ClinicalTrials.gov (NCT04938830). Outcome figures and adverse-event rates are extracted automatically from the registry's posted results and are provided for clinician reference, not as a substitute for the primary publication.