- Sanofi and AstraZeneca released new study results on Friday that showed their antibody drug for respiratory syncytial virus reduced hospitalizations for infection-related respiratory disease by 83% in infants.
- The drug, sold as Beyfortus, won approval in Europe in November as a preventive treatment for babies in their first RSV season and is due a decision by U.S. regulators in the third quarter. The results released Friday add to earlier data that showed the drug to be 75% effective in reducing RSV-related hospitalizations over placebo.
- RSV is a leading cause of hospitalization in infants, often overlapping with seasonal patterns for influenza and now COVID-19, too. It is estimated that more than 25,000 children under 5 years old die from RSV infections globally each year, with millions hospitalized.
The study results are the latest in a series of drugmaker successes against RSV after decades of unfruitful efforts, including a vaccine that worsened infections in the 1960s. A research breakthrough 10 years ago gave scientists and pharmaceutical companies a better target to aim at, leading to a flurry of new efforts.
Last week, the Food and Drug Administration approved the first vaccine for RSV, clearing GSK’s shot Arexvy for older adults, who are also vulnerable to the disease.
The shot could soon be followed onto the market by Pfizer’s vaccine, called Abrysvo. The U.S. regulator is expected to decide whether to clear the shot for preventing infections in older adults this month. An advisory committee supported its approval, but raised concerns about side effect risks.
As an antibody drug, Beyfortus, or nirsevimab, is designed to give passive, temporary immunization against RSV. The latest data from the Phase 3 study HARMONIE, which enrolled more than 8,000 infants, showed the single-injection drug reduced RSV infections requiring hospitalization by 83% in infants under 12 months of age compared to placebo.
In addition, it reduced hospitalizations by 58% related to all types of lower respiratory tract disease compared to placebo.
While Pfizer is aiming first for an approval in older adults, it is also developing the shot for use preventing RSV infections in newborns. The company has asked the FDA to approve the vaccine in pregnant women, an approach that is meant to pass on immunity to newborns and protect them through 6 months of age. Pfizer published study results supporting maternal use last month, and an FDA advisory panel will weigh in next week.
Meanwhile, GSK halted clinical testing of its maternal RSV candidate early last year, without giving much detail, but said analysis of the safety data was “ongoing.”
Moderna and Bavarian Nordic are also developing their own RSV vaccines in older adults, while Johnson & Johnson bowed out of the running in March, halting a large late-stage trial of its experimental shot.