Sanofi and AstraZeneca’s RSV Antibody Drug Gets FDA Approval, Adding New Weapon for Preventing Infant Infections

On July 17, the U.S. Food and Drug Administration approved nirsevimab (sold under the brand name Beyfortus) 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, and in children up to 24 months of age who remain vulnerable to severe disease through their second RSV season. 

Jointly developed by AstraZeneca (AZ) and Sanofi, nirsevimab is the first monoclonal antibody approved to provide protection against RSV infection in all infants. The duo plans to launch the product in the U.S. ahead of the upcoming 2023-2024 RSV season, entering the competition for the multi-billion dollar RSV prophylaxis and vaccine market.

Related article: Recent Highlights of the RSV Vaccine Battle, with More Regulatory Approvals in Sight  

A New Tool Addressing RSV-related Medical Needs

Previous studies have shown that RSV is the leading cause of hospitalization for infants under one year of age in the U.S., averaging nearly 16 times higher than the annual rate for influenza. Risk factors for RSV hospitalization include premature birth and younger chronologic age, along with several comorbid conditions associated with increased risk for RSV infection. Each year, there are approximately 590,000 cases of RSV disease among infants under one year old which require medical attention, including ambulatory care in doctors’ offices, urgent care, emergency room visits and hospitalizations. Based on a systematic literature review and analysis published in August 2022, the estimated annual cost of infant RSV treatment reaches $709.6 million, or $187 per birth on average. This indicates that RSV infections in newborns and infants have been posing a significant medical need in the country.

As one of the major competitors in the RSV prevention market, the AZ-Sanofi duo has been involved in the development and commercialisation of nirsevimab since 2017, describing it as a “potential game changer.” Back in November 2022, this single-dose long-acting antibody immunization secured an approval in the European Union for protecting newborns and infants during their first RSV season. In early January, the two companies announced that FDA’s Center for Drug Evaluation and Research (CDER) has accepted the Biologics License Application (BLA) for nirsevimab in 2022 and the agency has indicated it will work to expedite its review, setting the target action date for their decision as the third quarter of 2023.

Overwhelming Support for Clinical Efficacy from Expert Panel Leads to FDA Approval

In the Meeting of the FDA’s Antimicrobial Drugs Advisory Committee (AMDAC) on June 8, a panel of 21 experts voted unanimously that nirsevimab has a favorable benefit risk profile for the prevention of RSV-LRTD in newborns and infants ahead of or during their first RSV season. For children up to 24 months of age who remain vulnerable to severe RSV disease through their second RSV season, the antibody also gained an overwhelming 19 to 2 support regarding its efficacy. Overall, the AMDAC recommended approval of nirsevimab for use in passive immunization against RSV in newborns and infants.

The AMDAC based its recommendation on the robust nirsevimab clinical development program spanning three pivotal late-stage clinical trials, including results from the Phase 3 MELODY trial recently published in the New England Journal of Medicine. Across all clinical endpoints, a single dose of nirsevimab demonstrated high and consistent efficacy against RSV- LRTD sustained through the entire RSV season. In terms of safety, the antibody was well tolerated with a favorable safety profile that was consistent across all clinical trials.

As of July 2023, Beyfortus (nirsevimab) has been granted marketing authorization in the European Union, Great Britain and Canada for the prevention of RSV-LRTD in newborns and infants from birth through their first RSV season and is currently undergoing regulatory review in China, Japan and several other countries. Following the FDA approval, the AZ-Sanofi duo intends to launch the product in the U.S. before entering the 2023-2024 RSV season. “Beyfortus represents an opportunity for a paradigm-shift in preventing serious respiratory disease due to RSV across a broad infant population in the U.S.”, said Iskra Reic, Executive Vice President, Vaccines and Immune Therapies at AstraZeneca.

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Author

Richard Chau