Merck Announces FDA Acceptance of Biologics License Application for Clesrovimab

ited States and Canada, we strive to improve the health and well-being of people around the world. Today, we are excited to announce that the U.S. Food and Drug Administration (FDA) has accepted the Biologics License Application (BLA) for clesrovimab (MK-1654), our investigational prophylactic long-acting monoclonal antibody designed to protect infants from respiratory syncytial virus (RSV) disease during their first RSV season.

If approved, clesrovimab has the potential to make a significant impact by addressing the burden of RSV disease in the U.S. just in time for the 2025-26 season. This is a big step forward in our ongoing efforts to improve the health of infants and families.

Dr. Paula Annunziato, our senior vice president of infectious diseases and vaccines at Merck Research Laboratories, highlighted the importance of this regulatory milestone. She mentioned that despite recent advances in RSV prevention, there are still unmet needs when it comes to protecting infants from RSV. Dr. Annunziato emphasized that the acceptance of the BLA for clesrovimab, along with positive results from pivotal studies, represents significant progress in our goal of making this important intervention available for infants during their first RSV season.

The application for clesrovimab is based on data from the Phase 2b/3 CLEVER trial and interim results from the ongoing Phase 3 SMART trial. These trials have shown promising results in the prevention of RSV disease. If clesrovimab is approved, we anticipate that it will be available for ordering by healthcare professionals by July 2025, ensuring that it reaches infants in time for the 2025 RSV season.

Clesrovimab is an extended half-life monoclonal antibody designed to provide protection against RSV disease through a single dose, regardless of weight. It is being studied in healthy preterm, full-term, and at-risk infants to offer direct, rapid, and durable protection against mild, moderate, and severe RSV throughout their first RSV season.

At Merck, we are committed to ensuring global access to clesrovimab. We are actively developing regulatory and access strategies, as well as our supply chain, to make this intervention available in low- and middle-income countries. Our goal is to address the unmet needs for RSV prevention on a global scale.

RSV is a contagious virus that poses a significant health threat, especially to infants and older adults. It is a leading cause of hospitalization for healthy infants under a year old globally. RSV can lead to serious respiratory conditions and even death in some cases. The CDC reports that RSV season typically starts in the fall and peaks in the winter in most regions of the United States.

We are excited about the potential impact that clesrovimab could have in addressing the burden of RSV disease and are committed to working with regulatory agencies to make this important intervention available for infants in need.