Respiratory syncytial virus’s early surge this year has some healthcare officials concerned that this season could be a rough one. Infants, who are among the most vulnerable to infection from this pathogen, now have a new protective measure. The European Commission on Friday granted marketing authorization to an AstraZeneca and Sanofi drug that protects newborns from RSV infection in their first months of life.
The drug, an antibody called nirsevimab, is engineered to bind to the RSV’s fusion protein, preventing the virus from using that protein to enter cells. Partners AstraZeneca and Sanofi will market the new drug under the name “Beyfortus.”
The AstraZeneca and Sanofi drug protects differently than a vaccine. A vaccine triggers the immune system to produce an antibody, offering what is called active immunization. This type of immunity can take weeks to develop. Beyfortus is the protective antibody engineered in a lab. Administered directly to the infant, this passive immunity provides immediate protection.
AstraZeneca had previously commercialized a different RSV drug, Synagis. That antibody was developed to provide premature babies with protective antibodies that they lack. But Synagis has a half-life of about 20 days. It’s dosed as an intramuscular injection given before the RSV season starts, then once monthly during the RSV season.
AstraZeneca has described Beyfortus as a next-generation RSV antibody. It is engineered to have a long-half life—long enough to last the entire RSV season. That longer-life is intended to protect the baby during the first six months of life, the time when an infant is most vulnerable to RSV infection. Beyfortus can also address more babies as the product’s label covers infants broadly, not just those who are born prematurely.
The European Commission decision is based on clinical trial results showing that compared to a placebo, a single dose of Beyfortus met the main goal of reducing the incidence of medically attended lower respiratory tract infections during the RSV season. The companies reported that the drug’s safety was similar to a placebo. Also, clinical trial results showed that Beyfortus’s safety and tolerability were comparable to Synagis.
The Beyfortus vaccine alliance between AstraZeneca and Sanofi dates to 2017, when the antibody was still in mid-stage clinical testing. Sanofi paid its new partner €120 million up front; another €495 million was tied to the achievement of milestones. According to the deal terms, AstraZeneca took the lead on development and manufacturing activities. Sanofi will lead commercialization of the product. The partners share equally in development costs and profits from sales.
AstraZeneca and Sanofi aren’t the only companies trying to improve the way infants are protected from RSV. Earlier this week, Pfizer reported positive Phase 3 data for its RSV vaccine for infants, called RSVpreF. That vaccine offers a different form of passive immunization. This maternal vaccine is administered to a healthy mother, whose immune system produces antibodies that pass through the placenta and to the baby. Pfizer said it plans to seek FDA approval by the end of this year, followed by regulatory submissions with other global authorities in coming months.
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