Trial reportThe Journal of infectious diseases2025
Development of High-Titer Antidrug Antibodies in a Phase 1b/2a Infant Clesrovimab Trial Are Associated With RSV Exposure Beyond Day 150.
Trial report in The Journal of infectious diseases, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT03524118 (A Double-blind, Randomized, Placebo-controlled, Single Ascending Dose Study to Evaluate the Safety, Tolerability, and Pharmacokinetics of MK-1654 in Pre-Term and Full-Term Infants), which is not on this map. Cited by 5 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
A Double-blind, Randomized, Placebo-controlled, Single Ascending Dose Study to Evaluate the Safety, Tolerability, and Pharmacokinetics of MK-1654 in Pre-Term and Full-Term Infants
Who cites it
5 citing papers in PubMed.
- A Phase 1b/2a Trial of a Half-life Extended Respiratory Syncytial Virus Neutralizing Antibody, Clesrovimab, in Healthy Preterm and Full-term Infants.The Journal of infectious diseases · 2025Trial
- Structure and function of therapeutic antibodies approved by the US FDA in 2025.Antibody therapeutics · 2026Review
- CXCL13 and IL-33 as Immunomodulatory Adjuvants Combined with Respiratory Syncytial Virus Fusion (RSV F) Protein to Enhance Mucosal RSV Vaccination.Infection and drug resistance · 2026Review
- Determinants of success and failure of antibody-based strategies against respiratory viruses: insights from RSV and SARS-CoV-2.Frontiers in immunology · 2026Review
- Prophylactic monoclonal antibodies against respiratory syncytial virus in early life: An in-depth review of mechanisms of action, failure factors, and future perspectives.Pediatric allergy and immunology : official publication of the European Society of Pediatric Allergy and Immunology · 2025Review
Corrections and comments
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Authors and funding
11 authors.
Funding
Abstract
backgroundClesrovimab is a human half-life-extended monoclonal antibody in phase 3 evaluation for the prevention of respiratory syncytial virus (RSV) disease in infants. Antidrug antibodies (ADA) were observed at late time points in a phase 1b/2a study where clesrovimab was well tolerated with an extended half-life of approximately 45 days.
methodsSerum samples at days 150, 365, and 545 postdose were assayed for ADA titers. Samples with high ADA titers were characterized for their binding specificity to the Fab or the YTE portion of clesrovimab. RSV serum neutralization (SNA) titers were also measured on ADA-positive and ADA-negative infants. Additionally, a D25 (site Ø) competitive enzyme-linked immunosorbent assay (ELISA) was performed on ADA-positive available samples to determine RSV exposure. Local surveillance data was used to ascertain RSV circulation during the trial.
resultsHigh ADA titers were observed in a minority of infants at days 365 and 545 for all doses tested. Additionally, all high-titer ADA-positive infants had ADA directed towards the YTE epitope of clesrovimab. Moreover, these infants demonstrated robust RSV-SNA and had D25 competitive antibodies suggesting an RSV exposure after day 150, coinciding with the epidemiological data.
conclusionsRSV exposure in infants beyond day 150 after dosing is associated with ADA development and high RSV-SNA titers with no impact on pharmacokinetics. CLINICAL TRIALS REGISTRATION: NCT03524118.
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