Palivizumab

Dive Brief:An experimental antibody drug developed by Merck & Co. significantly reduced the incidence of disease due to respiratory syncytial virus infections as well as related hospitalizations in infants, the company said Thursday.Called clesrovimab, the antibody met all the goals of a Phase 2b/3 study testing it in more than 3,600 healthy pre- and full-term infants. A dose of clesrovimab lowered RSV disease incidence by 60%, and RSV-associated hospitalizations by 84%, compared to placebo through five months post-treatment.While three RSV vaccines are approved in the U.S. for older adults, only one antibody drug Sanofi and AstraZenecas Beyfortus is cleared for all infants entering their first RSV season. If approved, clesrovimab would compete with Beyfortus.Dive Insight:RSV is a significant public health concern for vulnerable populations, especially the elderly and newborns. Researchers estimate that nearly every child will be infected by the age of two. While infection typically only causes a mild, cold-like illness, it can be more serious and require hospitalization in some.Like Beyfortus, clesrovimab is designed to work as passive immunization. Merck is testing it as a single-dose shot for healthy preterm infants, full-term and at-risk infants of any weight. Beyfortus, meanwhile, comes in different dose strengths depending on the weight of an infant.In the Phase 2b/3 trial, healthy pre- or full-term infants from birth up to 1 year of age entering their first RSV season received either placebo or clesrovimab. Researchers then evaluated clesrovimabs safety and efficacy through five and six months following treatment.Merck had previously said the study succeeded and on Friday shared the more detailed data. Against endpoints measuring more severe disease, clesrovimab was around 90% effective versus placebo.Rates of adverse events and serious adverse events were comparable between antibody and placebo groups in the Phase 2b/3 study, Merck said. There were no treatment- or RSV-related deaths in that trial.The company also shared interim findings from a Phase 3 trial testing clesrovimab against an older antibody, Synagis, in infants at high risk of severe disease. Otherwise known as palivizumab, Synagis is cleared only for high-risk infants. In the study comparing Synagis and clesrovimab, the safety profile of the two drugs was comparable, according to Merck.The company aims to secure U.S. approval and make clesrovimab available as early as the 2025-2026 RSV season. '

Merck announced Thursday that its investigational antibody treatment, clesrovimab, demonstrated a 60.4 percent effectiveness in reducing infections associated with a specific type of respiratory syncytial virus (RSV) in infants. This seasonal injection regimen successfully achieved its primary goal in the mid to late phase of the trial, significantly reducing the incidence of medically care-required lower respiratory tract infections due to RSV in healthy infants under 1 year of age during the first RSV season. Merck further noted that clesrovimab also significantly reduced RSV-related hospitalizations by as much as 84.2% compared to placebo. The rate of side effects caused by the drug during treatment was comparable to that of the placebo group, and there were no deaths directly related to treatment or RSV during the study period. Merck previously announced in July that the vaccine had met the main goal of the study, but did not disclose details at the time. If approved, clesrovimab will compete in the U.S. market with Sanofi's (SASY.PA) and Astrazeneca's (AZN.L) Beyfortus, also an antibody therapy that prevents RSV infections in infants and children and requires a quarterly injection. In a separate late-stage study, Beyfortus was able to reduce the incidence of lower respiratory infections in infants requiring medical care by 74.5%. In addition, Synagis from Swedish orphan drug company Biovitrum (SOBIV.ST) is available as a treatment to prevent RSV, requiring monthly injections. Merck reported on Thursday that clesrovimab was on par with Synagis in terms of safety, a conclusion based on interim results from another late-stage study. Notably, Pfizer's RSV vaccine Abrysvo is already approved for use in pregnant women and is designed to prevent RSV infection in babies during the first six months of life. RSV often causes cold-like symptoms and is one of the leading causes of pneumonia and death in infants and the elderly. In the United States, the virus causes about 177,000 hospitalizations and 14,000 deaths each year.