The evolving science of Clesrovimab: pharmacological insights and clinical implications

Clesrovimab (MK-1654) is a next-generation monoclonal antibody (mAb) engineered for the prophylaxis of Respiratory Syncytial Virus (RSV or HRSV), a major etiological agent of lower respiratory tract infections in newborns, the elderly, and immunocompromised individuals. Having received regulatory approval in the United States and the United Arab Emirates in 2025, and currently under review in additional global markets, Clesrovimab has demonstrated robust immunoprophylactic efficacy in clinical trials. A single- dose administration provides durable protection, a significant reduction in RSV-associated infections and hospitalizations versus placebo, and a favorable safety profile with a lower incidence of adverse events (AEs) compared with existing standard-of-care interventions. This narrative review summarizes Clesrovimab’s molecular characteristics and clinical development, outlining key improvements observed in late-phase trials. Relevant data were identified through a literature search in PubMed, Scopus, and ClinicalTrials.gov (2018–2025) using the keywords “Clesrovimab,” “MK-1654,” and “respiratory syncytial virus”. A comparative analysis is presented with currently approved RSV-targeting mAbs, such as Palivizumab and Nirsevimab. The aim is to highlight Clesrovimab’s potential as a novel preventive strategy against RSV infection, emphasizing its enhanced binding affinity for the viral fusion (F) protein, superior biodistribution within the respiratory tract, and capacity to provide more effective and sustained protection. These features support its promising role in reducing RSV-related morbidity and mortality among high-risk populations.