FDA Panel Votes in Favor of Nirsevimab for RSV Disease Prevention in Infants

The Food and Drug Administration (FDA) Antimicrobial Drugs Advisory Committee (AMDAC) voted unanimously (21 “yes” to 0 “no”) that nirsevimab has a favorable benefit risk profile for the prevention of respiratory syncytial virus (RSV) lower respiratory tract disease (LRTD) in newborns and infants born during or entering their first RSV season.

The panel also voted 19 to 2 in support of the benefit-risk profile of nirsevimab for children up to 24 months of age who remain vulnerable to severe RSV disease through their second RSV season.

Nirsevimab is a long-acting anti-RSV monoclonal antibody that is administered as a single dose timed to the RSV season. The FDA panel reviewed efficacy and safety data from the nirsevimab clinical development program, which included the phase 3 MELODY trial (ClinicalTrials.gov Identifier: NCT03979313), the phase 2/3 MEDLEY trial (ClinicalTrials.gov Identifier: NCT03959488), and a phase 2b trial.

The MELODY trial compared a single intramuscular (IM) injection of nirsevimab to placebo in 1490 healthy infants who were born at a gestational age of at least 35 weeks. Findings showed that treatment with nirsevimab was associated with a statistically significant reduction in the incidence of medically-attended RSV-associated lower respiratory tract infection (LRTI) and a lower incidence of hospitalization for RSV-associated LRTI compared with placebo. 

In the randomized, double-blind, phase 2/3 MEDLEY trial, the safety and tolerability of nirsevimab was compared with palivizumab in approximately 925 infants with congenital heart disease, chronic lung disease, and/or prematurity before entering their first RSV season. Findings showed that nirsevimab demonstrated a similar safety and tolerability profile compared with palivizumab. 

The overall rates of adverse events were comparable between nirsevimab and placebo with a majority of adverse events being mild to moderate in severity. The most common adverse events were rash, fever and injection site reactions.

A regulatory decision is expected in the third quarter of 2023. Although not bound to the committee’s recommendations, the FDA does them into consideration when making decisions on approval.