Respiratory syncytial virus (RSV) continues to pose significant health risks for infants and immunocompromised individuals. At the recently concluded IDWeek 2024 in Los Angeles, pivotal studies on RSV prevention drew significant attention, focusing on the RSV-neutralizing antibody Clesrovimab and the mRNA-based RSV vaccine mRNA-1345. Below are insights into these key research findings.1. Clesrovimab for RSV Prevention in High-Risk Infants and Children
- Study Title: Safety, Efficacy, and Pharmacokinetics of Clesrovimab in Infants and Children at High Risk of Severe RSV Disease: A Randomized Controlled Phase III Trial (Abstract #167)
RSV infects approximately 12.9 million infants globally each year, causing significant respiratory infections and hospitalizations, particularly in high-risk groups like preterm infants and those with chronic conditions. Clesrovimab, an RSV-neutralizing antibody, targets a conserved site on the RSV F protein. A Phase III trial evaluated its safety, efficacy, and pharmacokinetics in high-risk infants and children, comparing it to palivizumab. Participants were randomized to receive either Clesrovimab or palivizumab in the first RSV season, followed by an open-label dose of Clesrovimab in the second season.
Both groups showed similar rates of adverse events, with no significant differences in serious events. The efficacy of Clesrovimab in preventing RSV-related lower respiratory tract infections requiring medical attention was comparable to palivizumab (3.6% vs. 3.0%), with similar hospitalization rates (1.3% vs. 1.5%). Notably, Clesrovimab exhibited an extended half-life of 44 days, supporting its use as a single seasonal dose.
In conclusion, Clesrovimab demonstrated good tolerability and efficacy similar to palivizumab in preventing RSV-related infections and hospitalizations in high-risk infants and children. These findings suggest Clesrovimab’s potential as a convenient, once-per-season prophylactic treatment for RSV.
2. mRNA-1345: A Promising mRNA-Based RSV Vaccine for High-Risk Children
- Study Title: Safety, Reactogenicity, and Immunogenicity of mRNA-1345 (an Investigational RSV Vaccine) in High-Risk Children Aged 2 to <18 Years (Abstract #168)
RSV is a major cause of respiratory infections in young children and a threat to older children with chronic conditions. Currently, no RSV vaccine is licensed for pediatric use. mRNA-1345, a single-dose mRNA vaccine, is being evaluated for safety and immunogenicity in high-risk children.
In a Phase II, observer-blinded trial, children aged 2 to <5 and 5 to <18 received either mRNA-1345 or placebo. Both age groups showed mild to moderate adverse reactions, with no serious vaccine-related events. By Day 29, a single dose of mRNA-1345 significantly increased RSV-neutralizing antibody titers. In the younger cohort, RSV-A titers increased by 5.9–12.7 times, and RSV-B titers by 4.3–8.9 times. For the older group, RSV-A titers rose by 8.2–15.8 times, and RSV-B titers by 4.7–8.0 times.
In conclusion, mRNA-1345 was well-tolerated and induced robust immune responses in both age groups, supporting its development as a safe and effective RSV vaccine for high-risk children.
Summary
Both studies underscore significant progress in RSV prevention for pediatric populations. Clesrovimab shows promise as a once-per-season option for infants at high risk of severe RSV disease, while mRNA-1345 demonstrates potential as an effective vaccine for high-risk children aged 2 to <18. These advancements mark essential steps towards enhancing RSV protection in vulnerable pediatric groups.
