Enflonsia (clesrovimab-cfor) / Merck (MSD) - LARVOL DELTA

Polybodies for the treatment of respiratory syncytial virus infection. (PubMed, Drug Discov Today) - "Although current prophylactics, such as palivizumab, nirsevimab, and clesrovimab, which target the RSV F protein, have enhanced early protection, more effective options with broader impact and longer-lasting efficacy are needed. In response to ongoing research efforts to develop new treatments for RSV, nanobodies have emerged as a promising option. Therefore, in this review, we discuss available therapies and explore the potential of nanobodies in treating RSV, with particular emphasis on the importance of polybodies [polyspecific and polyvalent antibodies (PsAbs and PvAbs)] in managing RSV infections."

Journal • Review • Infectious Disease • Respiratory Diseases • Respiratory Syncytial Virus Infections

Prophylactic monoclonal antibodies against respiratory syncytial virus in early life: An in-depth review of mechanisms of action, failure factors, and future perspectives. (PubMed, Pediatr Allergy Immunol) - "For over two decades, palivizumab was the only monoclonal antibody (mAb) available for prophylaxis, restricted to high-risk groups due to cost and limited duration of protection. Recent advances in structural virology and antibody engineering have led to the emergence of long-acting mAbs, notably nirsevimab and clesrovimab, which offer single-dose seasonal protection and are now shifting RSV prevention strategies from high-risk targeting to universal infant immunization...This review explores the molecular and immunological underpinnings of RSV-targeted mAbs, evaluates current real-world evidence, and outlines future directions-including bispecific antibodies and nanobody-based therapies-that could further transform RSV prophylaxis. Sustained genomic surveillance and a deeper understanding of host immunity will be crucial to preserve the long-term efficacy of these innovations in pediatric infectious disease prevention."

Journal • Review • Infectious Disease • Pediatrics • Pulmonary Disease • Respiratory Diseases • Respiratory Syncytial Virus Infections

Clesrovimab for the Prevention of Respiratory Syncytial Virus Lower Respiratory Tract Disease in Infants. (PubMed, J Pharm Technol) - " Clesrovimab offers simplified dosing, favorable safety, and potential cost savings compared with palivizumab and nirsevimab. 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."

Journal • Review • Infectious Disease • Pediatrics • Respiratory Diseases • Respiratory Syncytial Virus Infections

Comparison of the public health impact of RSV disease prevention options for infants: a static decision model of the us birth cohort. (PubMed, Expert Rev Vaccines) - "We compared the impact of these interventions on RSV-LRTD events and costs versus the previous standard-of-practice (SoP; palivizumab-only strategy). RSVpreF maternal vaccination would avert 76,915 RSV-LRTDs including 9,649 hospitalizations, equating to $345 million in total cost savings. While all three interventions are estimated to reduce RSV-LRTD burden in infants, all-infant protection with nirsevimab was estimated to avert more events and associated medical costs for all infant subgroups compared to clesrovimab or RSVpreF."

Journal • Respiratory Diseases • Respiratory Syncytial Virus Infections

Development of a Multidimensional HTA Evaluation for the Introduction of Clesrovimab in Pediatric RSV Prevention: An Integrated Methodological Approach (ISPOR-EU 2025) - "Clesrovimab appears to be a cost-effective option for RSV prevention. The HTA approach supports informed decisions and may promote equitable access and improved outcomes in the neonatal population."

Clinical • Infectious Disease • Pediatrics • Respiratory Diseases • Respiratory Syncytial Virus Infections

Respiratory syncytial virus. What's new in prevention? (PubMed, Semin Fetal Neonatal Med) - "Prevention of RSV lower respiratory tract infections (LRTI) in infants has been limited to general measures and palivizumab, a monoclonal antibody indicated for the highest risk groups...Likewise, novel extended half-life monoclonal antibodies, nirsevimab and the recently approved clesrovimab, opened the possibility of large-scale protection targeted to all infants born during the winter season and those <6 months at the beginning of it. Several RCTs and results from populations adopting nirsevimab prophylaxis demonstrated a large decrease in the incidence of RSV-LRTIs and a great impact in infant public health. Deployment of either strategies or in combination as part of immunization programs can be complement each other even as newer immunologic agents are being introduced."

Journal • Review • Infectious Disease • Pulmonary Disease • Respiratory Diseases • Respiratory Syncytial Virus Infections

Genetic variability of respiratory syncytial virus and its impact on monoclonal antibody binding sites: a national cross-sectional study during the 2023-2024 season. (PubMed, Int Immunopharmacol) - "This study provides a critical genomic snapshot of RSV in Italy prior to the introduction of vaccines and mAbs. Continuous surveillance is essential for monitoring viral evolution and supporting the long-term effectiveness of future immunization strategies."

Clinical • Journal • Observational data • Infectious Disease • Influenza • Respiratory Diseases • Respiratory Syncytial Virus Infections

Prevalence of Resistance-Associated Mutations in RSV F Protein Against Monoclonal Antibodies Prior to Widespread Implementation: Findings From a Prospective German Pediatric Cohort. (PubMed, Influenza Other Respir Viruses) - "Although the current risk of infections with escape-mutants appears to be low, our results underline the need for continued surveillance, as resistance-conferring mutations to new mAbs circulated and may be selected under selection pressure."

Journal • Infectious Disease • Pediatrics • Respiratory Syncytial Virus Infections

Merck Receives Positive EU CHMP Opinion for ENFLONSIA (clesrovimab) for the Prevention of Respiratory Syncytial Virus (RSV) in Infants During Their First RSV Season (Businesswire) - "he CHMP recommendation will now be reviewed by the European Commission (EC) for marketing authorization in the European Union (EU), Iceland, Liechtenstein and Norway, and a final decision is expected before the end of the year....The CHMP recommendation is supported by results from the pivotal Phase 2b/3 CLEVER trial (MK-1654-004) (NCT04767373)....and the Phase 3 SMART trial (MK-1654-007) (NCT04938830)..."

CHMP • EMA approval • Respiratory Syncytial Virus Infections

Clesrovimab in Infants and Children at Increased Risk for Severe RSV Disease. (PubMed, N Engl J Med) - No abstract available

Journal • Respiratory Syncytial Virus Infections

Clesrovimab for Prevention of RSV Disease in Healthy Infants. (PubMed, N Engl J Med) - P2/3 | "In healthy preterm and full-term infants, a single dose of clesrovimab reduced the incidence of RSV-associated medically attended lower respiratory infection and RSV-associated hospitalization, with a safety profile similar to that of placebo. (Funded by Merck Sharp and Dohme; CLEVER ClinicalTrials.gov number, NCT04767373.)."

Journal • Infectious Disease • Respiratory Diseases • Respiratory Syncytial Virus Infections

Evaluating the potential clinical and economic impact of Clesrovimab for infants in England and Wales (V-Congress 2025) - No abstract available

Clinical • HEOR

Safety, efficacy, pharmacokinetics, and pharmacodynamics of clesrovimab in infants at increased risk of severe RSV disease: Subgroup analysis of Japanese participants in the phase 3 SMART trial (MK-1654-007) (V-Congress 2025) - No abstract available

Clinical • P3 data • PK/PD data • Respiratory Syncytial Virus Infections

Clesrovimab: First Approval. (PubMed, Drugs) - "Clesrovimab received its first US approval on 9 June 2025 for preventing RSV lower respiratory tract disease in neonates and infants born during, or entering, their first RSV season. This article summarises the milestones leading to this first approval."

Journal • Respiratory Diseases • Respiratory Syncytial Virus Infections

Cost-Effectiveness Analysis of Clesrovimab for Protection against Infant Respiratory Syncytial Virus Disease in the United States (IDWeek 2025) - No abstract available

Cost effectiveness • HEOR • Infectious Disease • Respiratory Syncytial Virus Infections

Clesrovimab Efficacy through 6 Months during a Time of Changing SARS-CoV-2 Nonpharmaceutical Interventions (NPIs): Subgroup Analysis of the China Cohort in the Phase 2b/3 CLEVER Trial (IDWeek 2025) - No abstract available

Clinical • P2/3 data • P2b data • Infectious Disease • Novel Coronavirus Disease

Respiratory Tract Infections and Co-Infections Following Administration of the Respiratory Syncytial Virus (RSV) Antibody Clesrovimab versus Placebo: Analysis of the Phase 2b/3 CLEVER Trial (IDWeek 2025) - No abstract available

Clinical • P2/3 data • P2b data • Infectious Disease • Respiratory Syncytial Virus Infections

Clesrovimab Efficacy through 6 Months during a Time of Changing SARS-CoV-2 Nonpharmaceutical Interventions (NPIs): Subgroup Analysis of the China Cohort in the Phase 2b/3 CLEVER Trial (IDWeek 2025) - No abstract available

Clinical • P2/3 data • P2b data • Infectious Disease • Novel Coronavirus Disease

Use of Clesrovimab for Prevention of Severe Respiratory Syncytial Virus-Associated Lower Respiratory Tract Infections in Infants: Recommendations of the Advisory Committee on Immunization Practices - United States, 2025. (PubMed, MMWR Morb Mortal Wkly Rep) - "All infants should be protected against RSV-associated LRTI through use of one of these three products (i.e., maternal RSV vaccination or administration of nirsevimab or clesrovimab to the infant). No one product is preferred; the choice should be guided by parent preference, product availability, and timing of the infant's birth relative to the RSV season."

Clinical guideline • Journal • Infectious Disease • Pediatrics • Respiratory Diseases • Respiratory Syncytial Virus Infections

Phase I open-label study of the respiratory syncytial virus monoclonal antibody clesrovimab: Safety and tolerability in healthy Chinese participants. (PubMed, Hum Vaccin Immunother) - P2/3 | "No rash AESI from Day 1 through Day 42 postdose, and no serious AEs, deaths, study discontinuations or drug-related pauses were reported. These findings support the inclusion of a Chinese cohort in the global Phase IIb/III trial (NCT04767373) to evaluate the efficacy and safety of clesrovimab in healthy preterm and full-term infants."

Journal • P1 data • Immunology • Infectious Disease • Respiratory Diseases • Respiratory Syncytial Virus Infections

Clesrovimab (MK-1654) in Infants and Children at Increased Risk for Severe Respiratory Syncytial Virus (RSV) Disease (MK-1654-007) (clinicaltrials.gov) - P3 | N=1003 | Completed | Sponsor: Merck Sharp & Dohme LLC | Active, not recruiting ➔ Completed

Trial completion • Infectious Disease • Respiratory Diseases • Respiratory Syncytial Virus Infections

Clesrovimab (Enflonsia) for prevention of severe RSV infection in infants. (PubMed, Med Lett Drugs Ther) - No abstract available

Journal • Infectious Disease • Respiratory Diseases • Respiratory Syncytial Virus Infections

Clesrovimab-cfor. (PubMed, Am J Health Syst Pharm) - No abstract available

Journal

Evaluation of a monoclonal antibody against respiratory syncytial virus, Clesrovimab, in infants and children: Comprehensive rationale and study design for the late-stage clinical trials. (PubMed, Contemp Clin Trials) - P2/3, P3 | "The methodology of the accelerated late-stage development of clesrovimab, including the model-informed dose selection approach, the seamless enrollment in the phase 3 portion of CLEVER, and the extrapolation of efficacy from the population in CLEVER to the population in SMART, may be used to inform future trial designs where acceleration is needed to address an unmet medical need."

Journal • Infectious Disease • Pediatrics • Respiratory Diseases • Respiratory Syncytial Virus Infections

Respiratory syncytial virus immunization in children: The old, the new and what's just around the corner. (PubMed, Hum Vaccin Immunother) - "Until recently, immunization was limited to high-risk infants and children, including those born prematurely or with significant co-morbidities, via monthly dosing with the monoclonal antibody (mAb) palivizumab. Recent approvals of long-acting mAb nirsevimab and the maternal RSV pre-fusion F vaccine combined with other anticipated options such as long-acting mAb clesrovimab, and future pediatric vaccines, signal a shift in RSV immunization...We report findings from a survey assessing the level of immunization acceptance among Canadian parents. Provision of education through healthcare professionals, printed materials, parent groups, social media, and the internet were recommended."

Journal • Review • Infectious Disease • Pediatrics • Respiratory Diseases • Respiratory Syncytial Virus Infections