Topline results from phase IIb/III trial of clesrovimab (MK 1654), an investigational respiratory syncytial virus preventative monoclonal antibody for infants

In the trial, clesrovimab met its primary safety and efficacy endpoints, including reducing medically attended lower respiratory infections (MALRI) caused by RSV through Day 150. Detailed findings of the study will be presented at an upcoming scientific congress and Merck plans to file these data with global regulatory authorities.

“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."

About MK-1654-004 study; MK-1654-004 (NCT04767373) is a Phase IIb/III double-blind, randomized, placebo-controlled study to evaluate 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 include the incidence of participants with RSV-associated medically attended lower respiratory infection (MALRI) from Day 1 (post dose) to Day 150 as 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).