In August 2024 Pfizer announced positive top-line safety and immunogenicity results from substudy B of its ongoing Phase III clinical trial MONeT (RSV IMmunisatiON study for adulTs at higher risk of severe illness). The trial evaluates two doses of the ABRYSVO vaccine in immunocompromised adults aged 18 and older who are at risk of developing severe respiratory syncytial virus (RSV)-associated lower respiratory tract disease (LRTD). Pfizer states that the results “add to the growing body of evidence” suggesting that a single dose of the vaccine provides “strong immune protection against outcomes caused by RSV”.
The study
Adults who have immunocomprising conditions are at increased risk of developing RSV-LRTD. The substudy of the MONeT trial was designed to assess the safety and immunogenicity of two doses of ABRYSVO, administered one month apart, in four groups of immunocompromised adults:
- Those with non-small cell lung cancer
- Those on haemodialysis due to end-stage renal disease
- Those with autoimmune inflammatory disorder receiving active immunomodulator therapy
- Solid organ transplant recipients
203 adults were enrolled in the open-label study; approximately half were aged 18 to 59 and approximately half were 60 years or older.
ABRYSVO was “well-tolerated” in the trial, showing a safety profile “consistent with findings from other studies of the vaccine”. Although two doses were evaluated, a single 120 µg dose of ABRYSVO generated a “strong” neutralising response against both subtypes of RSV, RSV-A and RSV-B, in all cohorts and age groups in the study.
Encouraging data
Dr Annaliesa Anderson, Senior Vice President and Chief Scientific Officer, Vaccine Research and Development, Pfizer, highlighted that immunocompromised adults, such as patients with cancer or autoimmune disorders, have a “substantially increased risk of experiencing severe complications from RSV”. However, 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.”
For more on efforts to limit the damage caused by RSV in a range of subpopulations, join us at the Congress in Barcelona this October, and don’t forget to subscribe to our weekly newsletters here.
