Administrative Issues Delay FDA Decision on Moderna RSV Vaccine

The FDA has indicated that regulators will not be able to complete their review of the biologics license application (BLA) for mRNA-1345, Moderna's investigational respiratory syncytial virus (RSV) vaccine by the Prescription Drug User Fee Act (PDUFA) date of May 12, 2024. The delay is because of administrative issues and there are no issues related to vaccine safety, efficacy or quality that would prevent the approval.

Regulators are working to complete their review by the end of May 2024.

Moderna remains on track for mRNA-1345 to be reviewed at the CDC's Advisory Committee on Immunization Practices (ACIP) June 26-27, 2024, meeting, according to a company news release.

RSV is a common virus that can lead to potentially serious respiratory illness. Older adults, including those with underlying medical conditions such as diabetes and chronic heart and lung disease, are at increased risk of severe RSV illness and drive the majority of RSV hospitalizations. About 177,000 adults 65 years and older are hospitalized in the United States because of RSV.

mRNA-1345 is an investigational RSV vaccine that consists of a single mRNA sequence encoding for a stabilized prefusion F glycoprotein. The vaccine uses the same lipid nanoparticles as in the Moderna COVID-19 vaccines. When it launches, mRNA-1345 will be the only pre-filled, ready to use syringe. It will be indicated for adults ages 60 years of age and older.

The application is supported by data from a phase 3 study of about 37,000 adults. The study met its primary endpoint against RSV-associated lower-respiratory tract disease, with vaccine efficacy of 83.7% in those with two or more symptoms and vaccine efficacy of 82.4% in those with three or more symptoms.

Most adverse events were mild to moderate, and there were no cases of Guillain-Barre Syndrome. These data were published in December 2023 in the New England Journal Medicine.

Follow-up data from a phase 3 study with a median follow up of 8.6 months

Company officials said earlier this year that in addition to the United States, if other authorizations could follow and the company plans to launch the RSV vaccine in Australia and Germany this year and in other markets in 2025.

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Last year, the first two vaccines for RSV were approved for older adults and a separate vaccine was approved to prevent RSV infections in infants. GSK’s Arexvy, approved for adults in early May 2023, is an adjuvanted vaccine, which means it contains an ingredient to increase immune response. Arexvy is under review at the FDA to be used to prevent RSV in adults aged 50 to 59 who are at increased risk. The PDUFA date is June 7, 2024.

The second adult vaccine was approved a few weeks later. Pfizer’s Abrysvo is a bivalent RSV prefusion F (preF) vaccine that is composed of two preF proteins selected to optimize protection against RSV A and B strains. The FDA also approved Abrysvo to prevent RSV in infants.

Additionally, the FDA approved last year Sanofi and AstraZeneca’s Beyfortus (nirsevimab-alip), which prevents RSV in newborns and infants. Beyfortus is the first monoclonal antibody to protect infants through their first RSV season. Although designed to prevent disease like a vaccine, it is not a vaccine because it does not stimulate the immune system.