Merck, known as MSD outside of the United States and Canada, announced positive results from their Phase 2b/3 clinical trial for clesrovimab, a potential treatment for respiratory syncytial virus (RSV) in infants. The trial, conducted on healthy preterm and full-term infants aged birth to one year, showed that a single dose of clesrovimab significantly reduced the incidence of RSV-related medical events.
The trial met all its primary and secondary endpoints. Notably, clesrovimab reduced the incidence of RSV-associated medically attended lower respiratory infections by 60.4% compared to a placebo. Additionally, the treatment demonstrated a remarkable reduction in RSV-related hospitalizations (84.2%) and hospitalizations specifically for lower respiratory infections (90.9%). Furthermore, the incidence of severe cases requiring multiple indicators of lower respiratory infection severity was reduced by 88%. The safety profile of clesrovimab was comparable to the placebo, with no treatment or RSV-related deaths reported.
Preliminary data from an ongoing Phase 3 trial comparing clesrovimab to palivizumab, an existing preventative treatment for at-risk infants, also showed promising results. Clesrovimab demonstrated a safety profile comparable to palivizumab, and both treatments showed similar efficacy in reducing RSV-associated medical events in this interim analysis.
These findings suggest that clesrovimab could become a groundbreaking treatment option for RSV in infants, potentially offering a single-dose immunization for all infants regardless of their health status or weight. This could significantly reduce the burden of RSV on families and healthcare systems globally. Merck is engaged in discussions with health authorities worldwide, aiming to make clesrovimab available as early as the 2025-26 RSV season.
