Pfizer’s Abrysvo vaccine has demonstrated positive top-line safety and immunogenicity results in immunocompromised adults, according to findings from Substudy B of an ongoing Phase 3 clinical trial.
The study, dubbed MONeT (RSV Immunisation Study for Adults at Higher Risk of Severe Illness), is evaluating the impact of two doses of the bivalent RSV prefusion F (RSVpreF) vaccine. It focuses on adults aged 18 and older who are at high risk of severe respiratory syncytial virus (RSV)-associated lower respiratory tract disease (LRTD).
The trial specifically targets immunocompromised individuals, who are more susceptible to RSV-LRTD.
Substudy B aimed to assess the safety and efficacy of two doses of Abrysvo, administered one month apart.
The study included four groups of immunocompromised adults, those with non-small cell lung cancer, those on haemodialysis, those receiving immunomodulator therapy for autoimmune disorders, and solid organ transplant recipients.
Of the 203 participants, approximately half were aged 18 to 59, while the other half were 60 or older.
Abrysvo was well-tolerated, with a safety profile consistent with results from other studies of the vaccine.
While the trial investigated the impact of two doses, a single 120 µg dose of Abrysvo effectively produced a strong neutralising response against RSV-A and RSV-B in all age groups and cohorts, said the pharma major.
Pfizer intends to share these results at an upcoming scientific conference and publish them in a peer-reviewed journal, as well as submit the data to regulatory agencies for review.
Pfizer senior vice president and vaccine research and development chief scientific officer Annaliesa Anderson said: “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.
“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.”
In June 2024, Pfizer presented results from a study at an Advisory Committee on Immunisation Practices (ACIP) meeting involving 681 adults aged 18-59 with chronic conditions. This study found that the neutralising responses against RSV-A and RSV-B were comparable to those seen in the Phase 3 RENOIR study, which demonstrated Abrysvo’s efficacy in adults aged 60 and older.
Additionally, the US Food and Drug Administration (FDA) has approved Pfizer’s supplemental biologics license application for the ACT-O-VIAL presentation of Abrysvo.
This approval allows Pfizer to introduce a new reconstitution option to the market, complementing its existing needle-free kits. The ACT-O-VIAL System is a dual-component vial system designed to simplify the reconstitution of Abrysvo within a single, compact device.
In May 2023, the FDA approved Abrysvo for preventing lower respiratory tract disease caused by RSV in individuals aged 60 and older.
