Sanofi and AstraZeneca have gained the support of a US Food and Drug Administration (FDA) advisory panel for their experimental antibody therapy, nirsevimab, which can potentially prevent respiratory syncytial virus (RSV) infections in infants. During the panel's meeting, they unanimously voted in favour of using nirsevimab in newborns and infants to prevent infections in their first RSV season, while separately voting 19-2 for infants aged up to two years who are vulnerable to severe illness.
Currently, Swedish Orphan Biovitrum's (SOBIV) Synagis is the only approved preventive therapy in the US for high-risk infants against RSV. However, unlike Synagis, which is given as monthly injections, nirsevimab is a long-acting therapy expected to be given once every season to prevent infection regardless of additional medical conditions in infants.
"This is probably the closest thing to an RSV vaccine that we have and it really moves the field forward," said Nimish Patel, a panel member. According to two studies, nirsevimab was effective in preventing lower respiratory tract infections, as stated by the FDA staff reviewers.
The panel's vote comes shortly after another FDA panel's backing of Pfizer's maternal vaccine, which has boosted its chances of becoming the first shot to protect infants from RSV. However, it is unknown how nirsevimab works on infants whose mothers have received experimental RSV shots. "I think there will need to be studies that are done to figure out when one is more useful than the other," said panelist Karen Kotloff.
According to Morningstar analyst Dampen Conover, nirsevimab's peak sales are estimated to touch $2 billion. The FDA is expected to make a decision on the therapy by Q3.