FDA Approves Clesrovimab-cfor for Prevention of RSV in Infants
The therapy is the first and only RSV preventative option using the same dose regardless of patient weight.
The FDA approved clesrovimab-cfor (Enflonsia) for the prevention of respiratory syncytial virus (RSV) lower respiratory tract disease in newborns and infants born during or entering their first RSV season, Merck announced in a release.1 The therapy is the first and only RSV preventative option using the same dose regardless of patient weight.
FDA Approves Clesrovimab-cfor For Prevention of RSV in Infants / JHVEPhoto - stock.adobe.com
The approval of clesrovimab-cfor was based on data from the phase 2b/3 CLEVER (NCT04767373) trial, in which the therapy met its primary endpoint of a reduction in incidence of RSV-associated medically attended lower respiratory infections. The approval was also based on data from the phase 3 SMART (NCT04938830) trial, which showed rates of RSV-associated medically attended lower respiratory infection were comparable to palivizumab.
“RSV disease is the leading cause of infant hospitalization in the US and can lead to serious respiratory conditions like bronchiolitis and pneumonia,” Octavio Ramilo, an investigator on the CLEVER and SMART trials., said in a release.1 “Enflonsia combines dosing convenience with strong clinical data showing significant reductions in RSV disease incidence and hospitalizations, making it a promising new intervention to help protect infants from RSV.”
CLEVER was a double-blind, randomized, placebo-controlled phase 2b/3 trial that evaluated the efficacy and safety of clesrovimab-cfor in early and moderate preterm infants and late preterm and full-term infants entering their first RSV season. The primary study endpoint was the incidence of patients with RSV-associated medically attended lower respiratory infection from day 1 through day 150 after dosing.
The study cohort included 3632 patients who randomly received a single 105 mg dose of clesrovimab-cfor or placebo. Patients were included if they were a healthy early or moderate pre-term infant or late pre-term or full-term infant. Exclusion criteria included having a bleeding disorder or having received any vaccine or monoclonal antibody for the prevention of RSV.
The study found that clesrovimab-cfor reduced the incidence of RSV-associated medically attended lower respiratory infections through 5 months by 60.5%. The therapy also reduced RSV-associated hospitalizations through 5 months by 84.3%, with increasing efficacy as disease severity worsened.
Additionally, the safety profile of clesrovimab-cfor was seen to be comparable to placebo, with most adverse reactions being mild to moderate. The most common adverse reactions were injection-site erythema, injection-site swelling and rash.
Clesrovimab-cfor is a long-acting monoclonal antibody that was designed to provide rapid and durable protection against RSV through 5 months, which is the typical length of an RSV season. The therapy should not be given to infants with a history of serious hypersensitivity reactions to any of its ingredients.
Merck said in the release that it anticipates ordering of clesrovimab-cfor to begin in July, with shipments being delivered before the start of the 2025-2026 RSV season.
“Enflonsia provides an important new preventive option to help protect healthy and at-risk infants born during or entering their first RSV season with the same dose regardless of weight,” Dean Y Li, president of Merck Research Laboratories, said in a release.1 “We are committed to ensuring availability of Enflonsia in the US before the start of the upcoming RSV season to help reduce the significant burden of this widespread seasonal infection on families and health care systems.”
READ MORE: Infectious Disease Resource Center
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