Merck Submits BLA for RSV Prevention Drug, Aiming to Reduce Hospitalization Rate by Over 80%

Merck & Co. (MSD) announced today that the U.S. Food and Drug Administration (FDA) has accepted its Biologics License Application (BLA), aimed at protecting infants during their first respiratory syncytial virus (RSV) season from RSV disease. The application involves the investigational preventive long-acting monoclonal antibody Clesrovimab (MK-1654). The FDA has set a review completion date before June 10, 2025.

Clesrovimab is an investigational extended half-life monoclonal antibody used as a passive immunization method to prevent RSV disease. The application is based on the results of the pivotal 2b/3 clinical trial CLEVER, a randomized, placebo-controlled trial assessing the efficacy of a single dose of Clesrovimab in healthy premature and full-term infants. Additionally, this BLA includes interim results from the ongoing phase 3 clinical trial SMART, which evaluates the safety and efficacy of Clesrovimab compared to palivizumab in high-risk infants and children. Data from these trials were presented at the Infectious Diseases Week (IDWeek) conference in October 2024.

Research results indicate that Clesrovimab reduced RSV-related hospitalization rates and RSV-related lower respiratory infection (LRI) hospitalization rates by 84% and over 90%, respectively, significantly lowering RSV-related hospitalization rates by over 80%.