As GSK and Pfizer look to roll out their adult respiratory syncytial virus (RSV) vaccines later this year, Sanofi and AstraZeneca hope to join them on the market with an antibody designed to protect infants. But first, the partners will need to pass several regulatory milestones, including an FDA advisory committee discussion set for later this week.
In briefing documents ahead of Thursday's meeting of the FDA's Antimicrobial Drugs Advisory Committee, FDA staffers summarized the application package for nirsevimab.
After reviewing data in two large placebo-controlled studies called Trial 03 and Trial 04, the FDA reviewers said the drug's "efficacy was demonstrated in the overall population in both trials." But the agency flagged "limited enrollment" of infants older than 8 months of age, so the drug's risk-benefit profile for that group "may need additional consideration."
Aside from those two trials, Sanofi and AstraZeneca also ran a third study testing their RSV drug candidate against the existing RSV antibody option, Sobi's Synagis. That trial was called Trial 05.
On the safety side, the FDA said trial investigators found no adverse events of anaphylaxis in any of nirsevimab's clinical trials. Severe or serious skin reactions were "uncommon" in the studies, the FDA said. Fewer than 1% of participants in either the treatment arm or the control arm in the trials experienced drug-related rashes, as determined by trial investigators, the FDA said.
As for deaths, there were 12 among infants who received nirsevimab in the three late-stage studies. But none were determined by the FDA to be related to the study drug, according to the briefing documents.
Sanofi and AstraZeneca are seeking an approval for nirsevimab to protect against lower RSV-associated respiratory tract disease in infants born during or entering their first RSV season. They're also applying for approval in children up to 24 months of age who are still vulnerable during their second RSV season.
At the upcoming meeting, the FDA will ask its advisory committee to consider the drug's overall benefit-risk profile and to break down the data in various patient groups. Also, it's asking the experts to consider which data might be necessary to inform future regulatory considerations should maternal vaccines reach the market. Maternal vaccination is an approach to protect newborns by vaccinating their mothers.
In the U.S., nirsevimab lags the regulatory progress across the pond. In Europe, the med scored an approval as Beyfortus back in November.
Meanwhile, on the vaccine front, GSK and Pfizer recently won back-to-back FDA approvals for their rival adult vaccines. Now, the companies are gearing up for a meeting this month of the Centers for Disease Control Prevention's Advisory Committee on Immunization Practices, which will review data and make recommendations about how the vaccines should be used.
Aside from the adult vaccine, Pfizer is also working on a vaccination approach to protect infants through material immunization. The FDA is set to make a decision on that application in August.
The RSV season starts in the fall and peaks in the early winter, so all of the companies hope to pass the necessary regulatory milestones to make their products available later this year.