Merck announced yesterday that the FDA has approved ENFLONSIA (clesrovimab-cfor), a preventive monoclonal antibody, for the prevention of RSV lower respiratory tract disease in newborns and infants entering their first RSV season.
ENFLONSIA injection. Image courtesy of Merck & Co.
ENFLONSIA is the only RSV preventative option that is administered with the same 105 mg dose regardless of the patient’s weight. It is designed to provide protection for 5 months, the length of a typical RSV season.
“RSV disease is the leading cause of infant hospitalization in the U.S. and can lead to serious respiratory conditions like bronchiolitis and pneumonia,” said Dr. Octavio Ramilo, chair of the Department of Infectious Diseases at St. Jude Children’s Research Hospital and investigator for the CLEVER (MK-1654-004) and SMART (MK-1654-007) trials of ENFLONSIA. Ramilo added that the monoclonal antibody has “strong clinical data showing significant reductions in RSV disease incidence and hospitalizations.”
ENFLONSIA clinical trials
The FDA approval is based on results from the CLEVER and SMART trials. The CLEVER trial, a Phase 2b/3 clinical trial, demonstrated a reduction in RSV-associated medically attended lower respiratory infections by 60.5% and a reduction in RSV-associated hospitalizations by 84.3%.
The SMART trial was a Phase 3 trial which demonstrated that the safety profile of Enflonsia is comparable to palivizumab (SYNAGIS).
Other RSV preventions
ENFLONSIA’s main competitor will be Sanofi’s Beyfortus (nirsevimab-alip), which generated €1.7 billion ($1.8 billion) in sales last year. Sanofi plans to ramp up shipping of Beyfortus in the third quarter of the year to comply with demand for the upcoming RSV season.
Also on the market is SYNAGIS, which only protects infants for about a month. SYNAGIS is recommended to be administered every 28-30 days during the RSV season. Comparatively, ENFLONSIA is only administered once per RSV season.
Both SYNAGIS and Beyfortus have two doses, 50 mg and 100 mg, which are administered depending on the patient’s weight, while ENFLONSIA has only one 105 mg dose.
About RSV
RSV, a common virus that causes infections of the lungs and respiratory tract, is highly contagious and is more severe in infants and older adults. Two out of three infants will develop an RSV infection during their first year of life. The virus is the main cause of lower respiratory tract disease and the leading cause of hospitalization in infants globally. Each year in the United States, an estimated 58,000–80,000 children younger than 5 years old are hospitalized due to RSV, according to the CDC. RSV season typically occurs from November to March.
Filed Under: Biologics, clinical trials, Immunology, Pediatrics
