Sanofi-AstraZeneca’s preventive RSV therapy appears safe, says FDA staff

(Reuters) -The U.S. Food and Drug Administration’s staff reviewers on Tuesday raised no major safety concerns for Sanofi and partner AstraZeneca’s experimental therapy to prevent respiratory syncytial virus (RSV) infections in infants.

The RSV prevention antibody, nirsevimab, showed an overall favorable safety profile in clinical trials, the FDA staff said in documents published ahead of the health regulator’s advisory committee meeting on Thursday.

The companies are seeking approval for use of the therapy in infants and children up to 24 months of age to protect them against lower respiratory tract disease that could cause pneumonia and bronchiolitis.

There were 12 deaths among infants who received nirsevimab compared to 4 deaths in patients who received a placebo or an older antibody drug, but the FDA’s reviewers said it did not consider the deaths to be related to the therapy.

The staff said two studies showed the therapy was effective in preventing lower respiratory tract infections, but benefits and risks for babies older than eight months may need additional consideration given limited enrollment from that age group in the trials.

While RSV generally causes a mild illness, infants are among those at the greatest risk of severe disease from the highly contagious virus.

One to two out of every 100 babies below six months of age with RSV infection may need to be hospitalized, according to government data.

(Reporting by Raghav Mahobe and Mariam Sunny in Bengaluru; Editing by Krishna Chandra Eluri, Shounak Dasgupta and Shinjini Ganguli)