Pfizer Reports Topline Data for Abrysvo Against RSV in Younger High-Risk Adults

A single dose of the RSVPreF (Abrysvo; Pfizer) vaccine generated strong neutralizing responses in immunocompromised adults aged 18 years and older and was well tolerated, according to topline data reported today by Pfizer. The findings are the first from the company’s study of the vaccine’s protective properties against severe respiratory syncytial virus (RSV)-associated lower respiratory tract disease (LRTD) in this particularly high-risk population.¹

The prespecified open-label substudy B of the company’s ongoing pivotal phase 3 clinical trial, MONeT evaluated 2 doses of the vaccine, given 1 month apart, in 4 groups of immunocompromised adults: those with non-small cell lung cancer, on hemodialysis treatment of end-stage renal disease, with autoimmune inflammatory disorder receiving immunomodulatory therapy, and recipients of organ transplant. The data reported today on a single 120 µg dose of RSVPreF showed the robust neutralizing response against both RSV-A and RSV-B subtypes, across all cohorts and age ranges in the trial. Approximately half of the 200 participants in substudy B were aged 60 years or older.¹

The vaccine’s safety profile in the high-risk cohort was consistent with previously reported studies, according to Pfizer. The company stated its plan to submit the data for regulatory agencies for review.¹

“Immunocompromised adults, such as patients with cancer or autoimmune disorders, have a substantially increased risk of experiencing severe complications from RSV, yet there are currently no vaccines approved for those aged 18 to 59 in the US,” Annaliesa Anderson, PhD, Pfizer senior vice president and chief scientific officer, vaccine research and development, said in the statement. “We are encouraged by the positive top-line data from this study, which provide important evidence that ABRYSVO has the potential to address a significant unmet need in this vulnerable population.”¹

In April, Pfizer reported early data from MONeT² that demonstrated neutralizing responses against both A and B strains of the infection in adults aged 18 to 59 years with a range of chronic conditions, the trial’s substudy A. Those findings were noninferior to data reported earlier from Pfizer’s phase 3 RENOIR trial of RSVPreF in a cohort of adults aged 60 years and older. RENOIR served as the registration trial for approval of RSVPreF by the FDA in May 2023 in this older population.

In June the Advisory Committee on Immunization Practices (ACIP) of the CDC revised its guidance on RSV vaccination in older adults, recommending a single lifetime dose for those all persons 75 years and older and for adults aged 60 to 74 years who are at increased risk of sever RSV-LRTD.

The original ACIP recommendation made ahead of the 2023 RSV season, the first for which any vaccine against the infection was available, was for immunization of adults aged 60 years and older based on a “shared clinical decision making” (SCDM) model that encouraged a conversation between patient and clinician on the risks and benefits of the vaccination.²

In August 2023, the FDA approved labeling for use of bivalent RSVPreF in pregnant women at 32 through 36 weeks of gestation for prevention of RSV-LRTD and severe LRTD in infants from birth until age 6 months. The ACIP followed the approval in September with its recommendation for the maternal vaccine, which it states should be administered from September through January to coincide with the RSV season in most of the continental US.¹

In March 2024, Pfizer reported additional data from the RENOIR trial demonstrating “durable efficacy” of more than 80% over 2 seasons in the study population of adults aged 60 years and older.

Pfizer continues to explore broadening use of the RSV immunization and has initiated a clinical trial evaluating RSVPreF in children aged 2 to younger than 18 years who are at increased risk for RSV disease.

According to Pfizer, the findings from the MONeT substudy B will be presented at an upcoming scientific conference and published in a peer-reviewed scientific journal.

References
1. Pfizer announces top-line results of Abrysvo for RSC in immunocompromised adults. news release. Pfizer. August 12, 2024. Accessed August 12, 2024.
2. Halsey G. Pfizer: MONeT study topline data positive for Abrysvo in adults aged 18 to 59 years at high risk for RSV-LRTD. Patient Care. April 9, 2024. https://www.patientcareonline.com/view/pfizer-monet-study-topline-data-positive-for-abrysvo-in-adults-aged-18-to-59-years-at-high-risk-for-rsv-lrtd