Pfizer on Monday reported a “strong neutralizing response” against both subtypes of respiratory syncytial virus across all cohorts and age groups, according to topline data.
Pfizer said Monday a Phase III trial of its respiratory syncytial virus vaccine in immunocompromised adults met its objectives, as the company pursues a label expansion that could give it a brief advantage over rival GSK.
The vaccine, which Pfizer sells as Abrysvo, won FDA approval in adults aged 60 years and older in 2023. As it prepared to launch the vaccine in older adults, Pfizer began a Phase III trial intended to support the expansion of the label. One sub-study, which delivered results earlier in 2024, examined Abrysvo in people aged 18 to 60 years at high risk for respiratory syncytial virus (RSV). Another sub-study enrolled immunocompromised adults.
Pfizer designed the immunocompromised sub-study to assess the effect of giving two 120-µg doses of Abrysvo one month apart. Monday, the company said after a single dose it saw a “strong neutralizing response” against both subtypes of RSV across all cohorts and age groups in the 203-subject sub-study. Around half of the participants were aged 60 years or older.
The safety profile was consistent with the findings of other studies of the vaccine, the company said. Pfizer plans to present the data at an upcoming scientific conference and send the results to regulatory agencies for review.
Regulators are already reviewing data on Abrysvo in people aged 18 to 60 years at high risk for RSV. Pfizer has submitted the results, which the company generated in the other sub-study, to agencies in Europe and the U.S. to support the expansion of the Abrysvo label to cover people aged 18 to 59 years.
Receiving authorization for the label expansion could give Pfizer a brief advantage over GSK, which sells the RSV vaccine Arexvy. The FDA in June 2024 approved Arexvy for use in people aged 50 to 59 years who have a medical condition that increases their risk of severe RSV outcomes . GSK is testing Arexvy in adults aged 18 years and older but has yet to publish data. Readouts from the program are expected this year.
FDA approval is one of two key barriers to market access in the U.S. The other barrier is the CDC’s Advisory Committee on Immunization Practices (ACIP), which develops recommendations on the use of vaccines. Pfizer presented data from the first sub-study to the committee in June.
ACIP’s recommendations will influence the upcoming RSV vaccination season. Sales of Abrysvo fell to $56 million in the second quarter of 2024. Pfizer CEO Albert Bourla said on a call with analysts in July that the result was “in line with seasonal vaccine trends.” The third and fourth quarter results will provide a clearer picture of demand for Abrysvo and how the fight for market share between Pfizer and GSK is playing out.
GSK, Moderna and Pfizer are all looking at potential RSV vaccine sales slumps thanks to recently updated CDC guidelines regarding the use of shots in seniors. In June, the ACIP reviewed data on the RSV vaccines from all three companies, passing a unanimous motion recommending a single dose for adults aged 75 and older as well as for those who are 60 to 74 years old with an increased risk of severe RSV.
