Palivizumab

iStock, graphixchon Merck’s investigational antibody clesrovimab demonstrated more than 60% effectiveness in reducing some types of respiratory syncytial virus-associated infections in infants, while Pfizer’s RSV vaccine Abrysvo showed 90% effectiveness at preventing the most severe RSV cases in adults 60 years and older. At the ongoing IDWeek 2024 Conference in Los Angeles, Merck and Pfizer both presented new data for their respective prophylactic options for respiratory syncytial virus, touting strong protective effectiveness against the infection and related hospitalizations. Their findings come as the U.S. enters a new respiratory syncytial virus (RSV) season, which typically starts in fall and peaks during winter. According to the National Foundation for Infectious Diseases, RSV is the most common reason for hospitalization in children under 1 year , causing up to 80,000 admissions per year. The virus is also a major source of respiratory morbidity in older adults. Merck unveiled Phase IIb/III data for its investigational antibody clesrovimab, a single dose of which was administered to healthy preterm and full-term babies entering their first RSV season. The study’s primary efficacy outcome was the percentage of participants with RSV-associated medically attended lower respiratory infection (MALRI), defined as having at least one indicator of LRI or severity. More than 3,600 infants from birth to 1 year of age were enrolled. Results showed a 60.4% drop in RSV-associated MALRI at 150 days after dosing, compared with placebo. At this time point, clesrovimab also lowered RSV-associated hospitalizations by 84.2% and RSV-associated LRI hospitalizations by 90.9%. Merck backed these data up with additional analysis from a separate Phase III study, which compared the safety and efficacy of clesrovimab versus palivizumab in infants and children who are at heightened risk of severe disease. Findings demonstrated that rates of RSV-associated MALRI and hospitalizations were similar between treatment arms. Clesrovimab was also safe and well-tolerated, with no concerning serious toxicity signals and treatment- or RSV-related deaths, according to Merck. Paula Annunziato, senior vice president of infectious diseases and vaccines clinical research at Merck, in a statement called these findings “clinically meaningful,” which “highlight the potential for clesrovimab to lessen the significant impact RSV can have on infants and their families, as well as the strain on the healthcare system.” At IDWeek 2024, Pfizer unveiled results from a retrospective analysis of adults 60 years and older who presented to emergency care with severe disease. In the study population, immunization with the company’s vaccine Abrysvo showed 90% effectiveness at preventing the most severe RSV cases, according to Endpoints News . The retrospective study was conducted by Kaiser Permanente in California but was funded by Pfizer. These data come after the U.S. Centers for Disease Control and Prevention narrowed its RSV vaccination guidelines for seniors. Per a June 2024 communication, the agency now only recommends RSV shots for all older adults aged 75 and older. In the 60 to 74 age group, vaccination is only recommended for those at risk of severe disease. This change could have significant implications for the industry, with analysts forecasting a nearly 65% drop in RSV revenues. According to a July 2024 report from Airfinity , sales for RSV shots in the U.S. are now only projected to reach $1.7 billion by 2030, down from a previous estimate of $4.7 billion. Despite bleaker sales prospects, Pfizer continues to shore up the evidence base for Abrysvo. In addition to results presented at IDWeek 2024, the pharma in August 2024 announced that the vaccine can elicit a strong neutralizing response against the virus in immunocompromised adults.

Clesrovimab is a single dose extended half-life monoclonal antibody developed as a passive immunisation for the prevention of RSV. Image credit: Sergiy Palamarchuk / Shutterstock. MSD ( Merck & Co) is planning to get its respiratory syncytial virus (RSV) vaccine, clesrovimab, approved and launched before the next RSV season in 2025-26, after reporting positive results from a Phase IIb/III trial. The company first reported that the Phase IIb/III MK-1654-004 trial (NCT04767373) evaluating clesrovimab as a preventative treatment for RSV in infants met its primary endpoint in July. MSD has now presented data showing that the therapy met the primary endpoint by reducing the incidence of RSV-associated medically attended lower respiratory infections (MALRI) requiring at least one indicator of lower respiratory infections by 60% through the first five months after dosing compared to the placebo. The results were presented at IDWeek 2024 taking place from 16-19 October in Los Angeles. MSD noted that the company is “continuing to discuss these data with health authorities around the world with the goal of making clesrovimab available for infants as early as the 2025-26 RSV season”. If approved, clesrovimab’s main competitor will be AstraZeneca and Sanofi ’s Beyfortus (nirsevimab), which is approved in the US for preventing RSV lower respiratory tract disease (LRTD) in newborns and infants. GlobalData estimates that Beyfortus will eclipse clesrovimab sales due to its first-to-market advantage, with the former raking in $2.5bn in 2030 compared to $408m for the latter over the same period. GlobalData is the parent company of Pharmaceutical Technology . See Also: FDA approves AbbVie’s VYALEV for advanced Parkinson’s treatment Glaukos eyes FDA approval for ocular therapy after Phase III win Clesrovimab is a single dose extended half-life monoclonal antibody developed as a passive immunisation for the prevention of RSV. The placebo-controlled Phase IIb/III MK-1654-004 trial enrolled 3,632 infants under one year. Clesrovimab met its secondary endpoint by reducing RSV-associated hospitalisations over five months by 84.2%, compared to placebo. The therapy also met its tertiary endpoint of reducing RSV-associated LRTD hospitalisations by 90.9% versus placebo through five months. MSD also presented data from an interim analysis from the Phase III MK-1654-007 trial (NCT04938830) that compared clesrovimab to Sobi’s RSV monoclonal antibody vaccine Synagis (palivizumab). The study is evaluated the vaccines in infants and children at increased risk for severe RSV disease. At the time of interim analysis, 901 participants were enrolled in the trial. The results showed that clesrovimab had a comparable safety profile to Synagis. Additionally, the incidence rates of RSV-associated MALRI requiring at least one indicator of lower respiratory infections and RSV-associated hospitalisations were comparable between the two groups, 3.6% and 1.3% in clesrovimab and 3% and 1.5% in Synagis groups, respectively.