Merck & Co., Inc. (MRK) has announced promising outcomes from its Phase 2b/3 clinical trial (MK-1654-004), which examined clesrovimab—an investigational prophylactic monoclonal antibody crafted to safeguard infants during their first respiratory syncytial virus (RSV) season.
The Phase 2b/3 pivotal trial assessed the effects of administering a single dose of clesrovimab to healthy preterm and full-term infants, ranging in age from newborn to one year. The trial successfully met all predetermined endpoints, with consistent findings over both five and six-month durations. The occurrence of adverse events and significant adverse events was comparable between the clesrovimab and placebo groups, and the study reported no treatment-related or RSV-associated fatalities.
Clesrovimab notably achieved a reduction of over 84% in RSV-related hospitalizations (a secondary endpoint) and a reduction exceeding 90% in RSV-associated lower respiratory infection hospitalizations (a tertiary endpoint) within the first five months of the trial.
Merck also disclosed findings from an interim analysis of the MK-1654-007 trial, a Phase 3 study appraising the safety and efficacy of clesrovimab in comparison to palivizumab in infants and children who are at an elevated risk of severe RSV disease. The study's primary focus is on the safety and tolerability of clesrovimab for infants in their inaugural RSV season.
Interim results indicated that clesrovimab's safety profile aligns with that of palivizumab, with no serious adverse events linked to the medication reported so far. The incidence rates for RSV-associated medically attended lower respiratory illness (MALRI) necessitating at least one indicator of lower respiratory infection or severity, as well as RSV-related hospitalizations (secondary endpoints), were comparable between clesrovimab (3.6% and 1.3%, respectively) and palivizumab (3.0% and 1.5%, respectively) over a span of 150 days (five months).
