AstraZeneca, Sanofi's nirsevimab protects infants against RSV disease

AstraZeneca and Sanofi announced Monday that a Phase III study of nirsevimab met its primary endpoint, with the long-acting antibody significantly reducing the rate of lower respiratory tract infections requiring medical attention due to respiratory syncytial virus (RSV), compared to placebo, in healthy late preterm and term infants during their first RSV season. The companies noted that nirsevimab is the first potential immunisation to show protection against RSV in the general infant population in a late-stage trial.

The MELODY study randomised around 1500 infants to receive a single 50-mg or 100-mg intramuscular injection of nirsevimab or placebo at the RSV season start, with the trial designed to determine the incidence of medically attended lower respiratory tract infections due to RSV through 150 days after dosing. Meanwhile, an additional 1500 infants will be enrolled in the study in the Northern and Southern Hemispheres to complete the safety evaluation.

Change prevention landscape

According to AstraZeneca and Sanofi, the evaluation of the main goal was conducted earlier than anticipated as sufficient cases had been accrued prior to the COVID-19 pandemic. The companies added that top-line results also indicated that the safety profile for nirsevimab was consistent with previous trial data, with no clinically meaningful differences between the two groups. Further data from the MELODY study will be presented at an upcoming medical meeting.

William Muller, primary investigator of the study, remarked "these exciting trial data demonstrate the potential for nirsevimab to change the prevention landscape not only by providing protection to a broad population of infants across the full RSV season, but also by achieving this with a single dose."

Filings planned for 2022

Nirsevimab, formerly MEDI 8897, is being developed under a 2017 collaboration between AstraZeneca and Sanofi. The drug is also being investigated in the Phase II/III MEDLEY trial versus AstraZeneca and Swedish Orphan Biovitrum's Synagis (palivizumab) among preterm infants and children with chronic lung disease and congenital heart disease entering their first and second RSV seasons. Early data from the study are anticipated in the coming months, with regulatory submissions for the all-infant indication expected to begin in 2022.