US FDA Approves Merck'sBLA for Clesrovimab to Protect Infants from RSV

Merck announced that the US Food and Drug Administration (FDA) has accepted the Biologics License Application (BLA) for clesrovimab (MK-1654), the company's experimental long-acting monoclonal antibody aimed at safeguarding infants from respiratory syncytial virus (RSV) disease in their initial RSV season. The FDA has established a target action date of June 10, 2025, under the Prescription Drug User Fee Act (PDUFA).

“Despite recent advances in RSV prevention, unmet needs remain for additional effective interventions to help protect infants and continue to help address the burden RSV places on families and the healthcare system. This regulatory milestone, along with promising results from our pivotal studies demonstrating efficacy in the prevention of RSV disease, marks important progress toward our goal of having clesrovimab available in time for the 2025-26 RSV season,” said Dr. Paula Annunziato, senior vice president, infectious diseases and vaccines, global clinical development, Merck Research Laboratories. “We look forward to working alongside the FDA on the review of clesrovimab, which, if approved, would be the first and only single dose immunization for infants regardless of weight designed to protect them for the duration of their first RSV season.”

The application is backed by results from the crucial phase 2b/3 CLEVER trial (MK-1654-004), a randomized placebo-controlled study assessing a single dose of clesrovimab given to healthy preterm and full-term infants (from birth to 1 year old), along with interim findings from the ongoing phase 3 SMART trial (MK-1654-007) which examines the safety and efficacy of clesrovimab compared to palivizumab in infants and children at higher risk for severe RSV disease. Information from these trials was shared at IDWeek in October 2024.