Clesrovimab for the Prevention of Respiratory Syncytial Virus Lower Respiratory Tract Disease in Infants

Abstract

Objective: To assess the clinical utility of clesrovimab-cfor (Enflonsia^®), a newly Food and Drug Administration (FDA)-approved monoclonal antibody, for the prevention of respiratory syncytial virus (RSV) lower respiratory tract infections in infants. Data Sources: A literature search was conducted using the key words clesrovimab, RSV, pediatric, infant, and nirsevimab. Data were also extracted from Centers for Disease Control and Prevention (CDC), Advisory Committee on Immunization Practices (ACIP), FDA prescribing information, and manufacturer data were reviewed. Study Selection and Data Extraction: English-language studies assessing the pharmacokinetics, pharmacodynamics, efficacy, and safety of clesrovimab were included. Key clinical trials (CLEVER and SMART) and cost-effectiveness models were reviewed. Data Synthesis: Clesrovimab binds to a conserved site on the RSV F protein, targeting both pre- and postfusion forms. In the CLEVER trial, it reduced RSV-associated medical visits by 60.4% and hospitalizations by 84.2%. The SMART trial showed comparable efficacy and safety to palivizumab. Adverse events were mild and injection-site related. No cross-resistance was observed with variants resistant to other monoclonal antibodies. Pharmacokinetics support single-dose administration with a half-life of 44 days. Conclusion: Clesrovimab offers simplified dosing, favorable safety, and potential cost savings compared with palivizumab and nirsevimab. While nirsevimab has a longer half-life, clesrovimab’s unique binding site and room-temperature stability offer practical advantages. Lack of head-to-head comparisons and limited second-season data warrant further study. Clesrovimab is a promising addition to RSV prevention strategies, offering effective, safe, and accessible immunization for infants. Ongoing research will clarify its role in high-risk populations and broader clinical use.