FDA Panel Backs GSK’s RSV Vaccine for Older People

GSK Plc’s vaccine for respiratory syncytial virus won the support of a key panel of U.S. regulatory advisers for use in people aged 60 and older, as the drugmaker races against Pfizer Inc. to bring to market the first vaccine for RSV.

The panel of 12 outside advisers to the Food and Drug Administration voted unanimously on Wednesday that GSK’s data show the Arexvy vaccine is effective. The same committee voted 10-2 that company data show the shot is safe. By contrast, it had voted 7-4 with one abstention to recommend Pfizer’s vaccine as both safe and effective in preventing RSV.

The Vaccines and Related Biological Products Advisory Committee’s recommendations aren’t binding, but are often followed by the FDA.

“It’s a very strong vote for GSK,” Adam Barker, an analyst at Goodbody, said in an email. “The stronger efficacy profile in those at very high risk will be the dominant factor.”

Shares of GSK were up 0.2% in London on Thursday morning.

GSK has been vying with Pfizer over which drugmaker will become the first to reach the U.S. market with vaccines for the lung illness. The maker of the blockbuster shingles vaccine Shingrix, GSK is counting on new products like Arexvy as Chief Executive Officer Emma Walmsley narrows the pharmaceutical company’s focus on cutting-edge drugs and vaccines.

“Across the board data presented suggest both vaccines offer broadly similar levels of protection over one season,” Sean Conroy, an analyst at Shore Capital, wrote in a note to clients, adding that data covering two seasons are expected next quarter. “This could become an important differentiator, particularly given GSK’s vaccine is adjuvanted with the same AS01 immunostimulant used in Shingrix which recently demonstrated 10-year efficacy data.”

RSV causes hundreds of thousands of hospitalizations in older adults each year and can be especially serious for infants and older adults. Last year, GSK stopped trials for a vaccine against the RSV virus in pregnant women due to potential risks. The RSV vaccine market for adults could be worth up to $10 billion by 2032, according to projections by Bloomberg Intelligence.

Both GSK and Pfizer have produced strong data showing the vaccines are effective in adults 60 and older, although there’s relatively little evidence on how much the vaccines reduce hospitalizations from RSV. Late-stage trials showed GSK’s experimental shot was 83% effective in older adults, according to briefing documents released before the meeting. It was well tolerated, with side effects like fatigue and headache. Efficacy against severe RSV was 94%.

Safety concerns emerged about Guillain-Barre syndrome, a rare disorder that occurs when the body’s immune system attacks the nerves, sometimes resulting in temporary paralysis. In one study, a 78-year-old female was diagnosed with the syndrome in Japan, where there is a higher incidence in the population, according to Peggy Webster, vice president and head of vaccine safety at GSK. The same disorder occurred in two cases in Pfizer’s trial among close to 20,000 participants.

In another study, there were two cases of acute disseminated encephalomyelitis, a neurological disorder characterized by swelling in the brain and spinal cord. The complication occurred among people who received both RSV and the influenza vaccinations. The FDA considered that it may be related to one of the two, and panel members discussed whether it might be related to their joint administration.

Correct Methodology

One participant with the disorder, a 71-year-old male, was hospitalized and died. The FDA and GSK are currently discussing plans for a post-marketing safety study to assess the risk of Guillain-Barre, encephalomyelitis and similar conditions among people who receive with GSK’s shot.

“I don’t think we’re saying ignoring these cases is the correct methodology,” said Nicholas Geagan, a staff fellow at the FDA’s Division of Vaccines and Related Products Applications. “We are still reviewing the details of the cases and requesting further information to further quantify the cases themselves.”

If the FDA approves the vaccines, the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices will issue recommendations that could have a big impact on how and when they’re used, along with how much revenue the two companies ultimately generate from them.