Pfizer plots Abrysvo expansion with positive study in wide pool of adults at risk from RSV

As Pfizer races to grow the respiratory syncytial virus (RSV) vaccine market along with rival GSK, the company has been looking to expand its vaccine's reach. Now, armed with fresh data for Abrysvo in adults at higher risk of disease, the New York drugmaker is plotting a new approval filing.

Pfizer has unveiled positive top-line immunogenicity and safety results from the phase 3 MONeT trial testing Abrysvo in adults ages 18 to 59 at risk of developing severe RSV-associated lower respiratory tract disease (LRTD).

With the trial win in hand, Pfizer says it plans to submit the data to regulatory agencies and request an expansion of the shot’s current indication to include people ages 18 and up, according to a Tuesday press release.

Abrysvo won a string of approvals last year alongside landmark RSV immunization offerings from GSK plus Sanofi and AstraZeneca. Pfizer’s shot snagged is initial FDA nod in late May, which covered the use of Abrysvo to prevent LRTD caused by RSV in adults ages 60 and older. In August, the vaccine was approved in the U.S. to protect babies for the first six months of life through vaccination of women who have been pregnant for 32 to 36 weeks.

Abrysvo’s ability to protect infants was backed up by the Centers for Disease Control and Prevention in late September, when the agency’s Advisory Committee on Immunization Practices voted 11-1 in favor of recommending Abrysvo as a maternal vaccine.

Meanwhile, the latest data could substantially increase Abrysvo’s reach.

Among U.S. adults 18 to 49 years old, nearly 10% have some form of chronic condition—such as asthma, diabetes or chronic obstructive pulmonary disease—that puts them at risk of severe RSV disease. That rate ticks up to 24.3% among people between the ages of 50 and 64, Pfizer explained in its release.

To date, no RSV vaccine has been approved in adults between the ages of 18 to 59, the New York-based drugmaker noted.

According to Pfizer’s top-line results, Abrysvo charted a noninferior response in people between 18 and 59 years old compared to its performance in the RENOIR study, which evaluated the shot in older adults. The company did not reveal detailed results from the study on Tuesday.

Pfizer’s MONeT study looked at Abrysvo’s performance across two subgroups. The trial enrolled 681 adults with chronic medical conditions for substudy A, plus another 200 who were immunocompromised for substudy B. Patients who got Abrysvo in substudy A received a single dose, while those in substudy B received two.

Pfizer’s Abrysvo was the second RSV immunization out of the gate last year following GSK’s nod for Arexvy in seniors in early May. Arexvy’s approval made GSK’s shot the world’s first approved RSV vaccine for adults. In July, Sanofi and AstraZeneca won approval for a slightly different type of RSV immunization in the form of the antibody nirsevimab, which goes by the brand name Beyfortus.

Beyfortus is specifically approved to prevent RSV-associated LRTD in newborns and infants during or entering their first RSV season, plus young kids up to 24 months old who remain at risk of RSV through their second disease season.

Pfizer, for its part, wasn't too thrilled with the early stage of its Abrysvo rollout. Earlier this year at the J.P. Morgan Healthcare Conference, the company’s CEO, Albert Bourla, Ph.D., called Abrysvo a “bad launch” for Pfizer. At the time, Bourla also said the company was looking to boost Abrysvo’s market share by establishing RSV vaccination as a year-round “discussion.”

Still, the company managed to partially close the sales gap with vaccine rival GSK in the fourth quarter. For all of 2023, Abrysvo generated $890 million, versus roughly $1.5 billion for GSK’s Arexvy.