On heels of FDA approval, trial results set up GSK's RSV vaccine for label expansion

Five months after becoming the first company to secure FDA approval for a respiratory syncytial virus (RSV) vaccine, GSK is taking steps toward expanding its label for Arexvy.

On Wednesday, the company revealed that a study investigating Arexvy’s effectiveness in adults ages 50 to 59 has achieved its two primary objectives. The results could pave the way for the shot to be approved for this age group. The FDA has already endorsed it for people 60 and older.

In adults ages 50 to 59 who are at an increased risk for RSV lower respiratory tract disease because of underlying medical conditions, Arexvy triggered an immune response that was non-inferior to those seen in subjects 60 and older. The trial also met its other co-endpoint, showing Arexvy achieved the same standard in those 50 to 59 who don't have underlying medical conditions.

“We will submit these data for regulatory review as quickly as possible with the goal of offering adults in this age group the option of a vaccine for the first time,” Tony Wood, GSK’s chief scientific officer, said in a release.

In addition, GSK will present the results today at the CDC’s Advisory Committee on Immunization Practices (ACIP) meeting. The company is eyeing a label expansion in the U.S. in 2024, it said.

GSK gained its green light for Arexvy based on a trial that showed 82.6% efficacy against RSV and 94.1% effectiveness in preventing severe disease.

A few weeks later, Pfizer scored an FDA nod for its RSV bivalent vaccine Abrysvo in adults 60 and older. Pfizer's RENOIR trial showed 66.7% protection versus RSV and 85.7% effectiveness against severe disease.

Three months later, the FDA also signed off on Abrysvo for women in their 32nd to 36th week of pregnancy to protect their soon-to-be-born babies through the first six months of their lives.

That green light came after the FDA gave a thumbs up in July to Sanofi and AstraZeneca’s Beyfortus as a preventative for RSV lower respiratory tract disease in infants entering their first RSV season and those who remain vulnerable entering their second RSV season.

In July, a report from GlobalData predicted that GSK will be the market leader in RSV, with the total market reaching $9 billion in 2029. The analysts see Moderna, which is developing an mRNA vaccine for RSV, to run a close second to GSK.