Merck announced positive topline results from its Phase 2b/3 clinical trial evaluating clesrovimab (MK-1654), an investigational prophylactic monoclonal antibody for preventing respiratory syncytial virus (RSV) disease in infants. The trial (MK-1654-004) met its primary safety and efficacy endpoints, including reducing medically attended lower respiratory infections (MALRI) caused by RSV through Day 150.
Clinical Trial Details
The Phase 2b/3 trial (NCT04767373) was a double-blind, randomized, placebo-controlled study. It evaluated the safety and efficacy of clesrovimab in healthy preterm and full-term infants. Participants were randomized to receive either a single dose of clesrovimab or placebo. The primary endpoints included the incidence of participants with RSV-associated MALRI from Day 1 (post dose) to Day 150, compared to placebo, and safety. Safety measures assessed included the percentage of participants with any injection-related adverse events (AEs), AEs of special interest (AESIs), solicited systemic AEs, or serious adverse events (SAEs).
Clesrovimab (MK-1654) Overview
Clesrovimab is an investigational extended half-life monoclonal antibody (mAb) developed as a passive immunization for the prevention of RSV-associated MALRI. It is being studied in infants (pre-term and full-term) to provide rapid, durable protection through their first RSV season with a single, fixed-dose administration.
The Burden of RSV
RSV is a contagious virus causing widespread seasonal infection with a worldwide burden in infants and older adults. Globally, it is the leading cause of hospitalization for healthy infants under one year old. RSV can lead to serious respiratory conditions like bronchiolitis and pneumonia, causing an estimated 101,000 deaths a year worldwide in children under five.
Expert Commentary
"RSV is highly contagious and can cause inflammation in the airways of infants leading to difficulty breathing. As a widespread illness globally, RSV is the leading cause of hospitalization for healthy infants," said Dr. Paula Annunziato, senior vice president, infectious diseases and vaccines, Global Clinical Development, Merck Research Laboratories. "We are encouraged by these findings and look forward to working with regulators to provide a new option to help address the impact of RSV on infants and their families."
Merck plans to present detailed findings of the study at an upcoming scientific congress and file these data with global regulatory authorities.
