Detailed results from the MELODY Phase III trial showed a single dose of AstraZeneca and Sanofi’s nirsevimab met the primary efficacy endpoint reducing the incidence of medically attended lower respiratory tract infections (LRTI) caused by respiratory syncytial virus (RSV) by 74.5%, compared to placebo.

The trial involved healthy term and late preterm (gestational age ≥35 weeks) infants entering their first RSV season.

The MEDLEY trial

Additionally, the MEDLEY Phase II/III trial, which evaluated safety and pharmacokinetics of nirsevimab in infants with congenital heart disease (CHD), chronic lung disease (CLD) and prematurity entering their first RSV season, demonstrated nirsevimab had a similar safety and tolerability profile compared to Synagis(palivizumab).

Serum levels of nirsevimab following dosing (on day 151) in this trial were comparable with those observed in the MELODY Phase III trial, indicating similar protection in this population to that in the healthy term and late preterm infants is likely. Synagis is currently the only available preventative option for RSV.

Nirsevimab

Nirsevimab is an investigational long-acting antibody designed to protect all infants through their first RSV season with a single dose. It is the first potential immunisation to show protection against RSV in the general infant population in a Phase III trial.

“Respiratory syncytial virus is a leading cause of lower respiratory tract infections, such as bronchiolitis or pneumonia, as well as hospitalisations in infants. These data show for the first time, the potential to significantly protect all infants through their first respiratory syncytial virus season with a single dose immunisation and we look forward to working with health authorities to bring nirsevimab to infants as quickly as possible,” says Mene Pangalos, Executive Vice President, BioPharmaceuticals R&D, AstraZeneca.

MELODY trial results were published in the New England Journal of Medicine (NEJM). Details from the MEDLEY trial were also published in the NEJM. Regulatory submissions began in the first half of 2022.

Photo of Mene Pangalos: AstraZeneca