FDA advisors back Beyfortus for RSV prevention

An FDA advisory committee has voted in favour of approving AstraZeneca and Sanofi’s one-shot antibody treatment to prevent respiratory syncytial virus (RSV) disease in infants, several months after the drug was cleared for marketing in Europe.

The panel voted 21 to zero that Beyfortus (nirsevimab) appears to be safe and effective at preventing RSV infections in newborns and infants as they face their first RSV season, setting the drug up to become the first single-dose option on the market with an all-comer label.

Advisors also voted by 19 to two that Beyfortus had an acceptable benefit and risk profile in children up to 24 months of age who remain vulnerable to RSV for a second season, giving AZ the hope of even broader labelling for the drug when the FDA makes its decision sometime in the third quarter of this year.

In Europe, Beyfortus is currently approved for use in the prevention of RSV lower respiratory tract infections in all children, during the first RSV season only.

“Most babies hospitalised with RSV are born at term and healthy, which is why interventions specifically designed to protect all infants are likely to result in the greatest impact,” said Sanofi’s vaccines chief, Thomas Triomphe.

Sobi’s Synagis (palivizumab) – originally developed and sold by AZ in the US – is currently the only drug approved to provide passive prophylaxis against RSV, but is restricted to use in newborns and infants at elevated risk of RSV complications, and has to be given monthly.

The former blockbuster – first approved back in 1998 – is still making solid sales, despite losing patent protection, with AZ booking $578 million from the drug last year. Meanwhile, there are a wide range of sales predictions for Beyfortus, ranging from less than $1 billion to multiple billions of dollars per year.

That largely reflects the uncertainty surrounding the prospects for Pfizer’s RSV vaccine, which is already approved as Arexvy for people aged 60 and over, and under FDA review as a maternal vaccine designed to transfer protection to newborns during pregnancy. It was recommended for approval by the advisory committee last month.

Assuming both are approved, there is some debate about whether it is better to vaccinate the mother or medicate the child for RSV prevention, but overall the view seems to be that there is plenty of room in the market for both approaches.

Some market observers point to stronger efficacy data with Beyfortus than Pfizer’s shot, particularly on severe disease, as well as clinician familiarity with use of antibodies. That could drive multi-billion-dollar sales, they suggest, with GlobalData recently putting the tally at $3 billion at peak.

There are still some questions to be answered about the possibility that both might end up being used in some cases, which on the one hand might provide additional protection, but also might lead to safety issues.

In the pivotal MELODY trial, Beyfortus reduced the incidence of medically attended lower respiratory tract infections caused by RSV by 74.5% compared to placebo, while in the MEDLEY study it was found to be at least as effective as Synagis in protecting pre-term infants or those with chronic lung disease (CLD) or congenital heart disease (CHD) from the virus.

Sanofi leads the commercialisation effort for Beyfortus globally, with AZ co-promoting the drug in some markets, including the UK, Germany, Italy, Spain, Japan, and China. The company hasn’t reported any sales figures for the drug yet.

Worldwide, RSV infections lead to more than three million hospitalisations and almost 60,000 deaths in children under five years of age every year, with around half of fatalities in infants less than six months.

Photo by Yousef Espanioly on Unsplash.