Merck’s Clesrovimab Shows Promising Results in Preventing RSV Disease and Hospitalizations in Infants

Efficacy:
Clesrovimab, Merck's investigational prophylactic monoclonal antibody, significantly reduced the incidence of RSV-associated medically attended lower respiratory infections (MALRI) by 60.4% and RSV-associated hospitalizations by 84.2% through 5 months compared to placebo.

Safety:
The Phase 2b/3 trial showed that clesrovimab had a comparable safety profile to the placebo group, with no treatment or RSV-related deaths reported.

Comparison to Palivizumab:
In the Phase 3 trial (MK-1654-007), clesrovimab demonstrated a comparable safety profile to palivizumab, with similar incidence rates of RSV-associated MALRI and hospitalizations.

Market Potential:
Merck plans to file these data with global regulatory authorities and aims to make clesrovimab available for infants as early as the 2025-26 RSV season, positioning it to compete with AstraZeneca and Sanofi’s Beyfortus (nirsevimab).

Clinical Trial Details:
The Phase 2b/3 trial (MK-1654-004) enrolled 3,632 participants and evaluated the safety and efficacy of a single dose of clesrovimab in healthy preterm and full-term infants entering their first RSV season.